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<div align="center"> <img height="200" src="images/plugin-logo.png"> <h1 align="center"> <a href="https://github.com/webdiscus/html-bundler-webpack-plugin">HTML Bundler Plugin for Webpack</a><br> <sub>All-in-one Web Bundler</sub><br> </h1> </div>

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This plugin is all you need to generate a complete single- or multi-page website from your source assets.

The plugin automates the processing of source files such as JS/TS, SCSS, images and other assets referenced in an HTML or template file. This plugin will generate an HTML file containing all the necessary links to JS, CSS, images and other resources.

Why use the HTML Bundler Plugin?

This plugin is a powerful alternative to html-webpack-plugin and a replacement for many plugins and loaders.

The HTML Bundler Plugin works a bit differently than html-webpack-plugin. It doesn't just inject JavaScript and CSS into an HTML. Instead, it resolves all the source files of the assets referenced directly in the template and ensures the generated HTML contains the correct output URLs of resources after Webpack processes them. Additionally, CSS extracted from styles imported in JS can be injected into HTML as a <link> tag or as an inlined CSS.

<h3 align="center"> 📋 <a href="#contents">Table of Contents</a> 🚀 <a href="#install">Install and Quick Start</a> 🖼 <a href="#usage-examples">Usage examples</a> 🔆 <a href="#whats-new">What's New</a> </h3> <!-- #### 📋 [Table of Contents](#contents) 🚀 [Install and Quick Start](#install) 🖼 [Usage examples](#usage-examples) -->

💡 Highlights

See full list of features.

HTML template as entry point

<center> <img width="830" style="max-width: 100%;" src="images/assets-graph.png" alt="assets graph"> </center>

The HTML Bundler generates static HTML or template function from various templates containing source files of scripts, styles, images, fonts and other resources, similar to how it works in Vite. This plugin looks at the template files in entry option to start building the bundle. The source files of dependencies (scripts, styles, etc.) can be defined directly in the template.

The plugin resolves source files of assets in templates and replaces them with correct output URLs in the generated HTML. The resolved assets will be processed via Webpack plugins/loaders and placed into the output directory. You can use a relative path or Webpack alias to a source file.

A template imported in JS will be compiled into template function. You can use the template function in JS to render the template with variables in runtime on the client-side in the browser.

<!-- This plugin is an advanced replacement of [html-webpack-plugin](https://github.com/jantimon/html-webpack-plugin) and many other [plugins and loaders](#list-of-plugins). -->

For example, using source asset files is HTML template ./src/views/index.html:

<html>
  <head>
    <!-- relative path to SCSS source file -->
    <link href="../scss/style.scss" rel="stylesheet" />
    <!-- relative path to TypeScript source file -->
    <script src="../app/main.ts" defer="defer"></script>
  </head>
  <body>
    <h1>Hello World!</h1>
    <!-- relative path to image source file -->
    <img src="../assets/images/picture1.png" />
    <!-- Webpack alias as path (src/assets/images/) to image source file -->
    <img src="@images/picture2.png" />
  </body>
</html>

The folder structure of the example:

./src/views/index.html
./src/app/main.ts
./src/scss/style.scss
./src/assets/images/picture1.png
./src/assets/images/picture2.png
<!-- ``` src/ ├── views/ │ └── index.html ├── app/ │ └── main.ts ├── scss/ │ └── style.scss └── assets/ └── images/ └── picture1.png └── picture2.png ``` -->

Simple and clear Webpack configuration:

const path = require('path');
const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');

module.exports = {
  output: {
    path: path.resolve(__dirname, 'dist'),
  },

  plugins: [
    new HtmlBundlerPlugin({
      // specify the entry points for HTML pages (or a template)
      entry: {
        index: 'src/views/index.html', // save generated HTML into dist/index.html
      },
      js: {
        filename: 'js/[name].[contenthash:8].js', // JS output filename
      },
      css: {
        filename: 'css/[name].[contenthash:8].css', // CSS output filename
      },
    }),
  ],
  
  module: {
      rules: [
        {
          test: /\.s?css$/,
          use: ['css-loader', 'sass-loader'],
        },
        {
          test: /\.(ico|png|jp?g|svg)/,
          type: 'asset/resource',
        },
      ],
    },
};

See full list of all plugin options.

Open an example in StackBlitz

🦖 Mozilla already uses this plugin to build static HTML files for the Mozilla AI GUIDE site.

The plugin has been actively developed for more than 2 years, and since 2023 it is open source.
Please support this project by giving it a star ⭐.

❤️ Sponsors & Patrons

Thank you to all our sponsors and patrons!

<a href="https://www.jetbrains.com/"><img src="https://avatars.githubusercontent.com/u/878437?s=50&v=4" title="JetBrains" alt="JetBrains"></a> <a href="https://github.com/getsentry"><img src="https://avatars.githubusercontent.com/u/1396951?s=50&v=4" title="Sentry" alt="Sentry"></a> <a href="https://github.com/stackaid"><img src="https://avatars.githubusercontent.com/u/84366591?s=50&v=4" title="StackAid" alt="StackAid"></a> <a href="https://github.com/pirang"><img src="https://avatars.githubusercontent.com/u/6986749?s=50&v=4" title="Pirang" alt="Pirang"></a> <a href="https://www.patreon.com/user?u=96645548"><img src="https://c10.patreonusercontent.com/4/patreon-media/p/user/96645548/020234154757463b939824efe62db137/eyJ3IjoyMDB9/1.jpeg?token-time=2145916800&token-hash=GYnR3xvy7qBr2w1CihOfDOq87nOr4AbuW0ytvwg7Kgs%3D" width="50" title="Buckley Robinson"></a> <a href="https://github.com/MarcelRobitaille"><img src="https://avatars.githubusercontent.com/u/8503756?s=50&v=4" title="Marcel Robitaille" alt="Marcel Robitaille"></a> <a href="https://github.com/kannwism"><img src="https://avatars.githubusercontent.com/u/18029781?s=50&v=4" width="50" title="Marian Kannwischer (kannwism)"></a> <a href="https://www.patreon.com/user?u=96645548"><img src="https://c10.patreonusercontent.com/4/patreon-media/p/user/43568167/0ef77126597d460c9505bdd0aea2eea9/eyJ3IjoyMDB9/1.png?token-time=2145916800&token-hash=7izh1FZTToAqf4Qks3Qrk8YcNbGymF-sBi0hkK_aJO8%3D" width="50" title="Raymond Ackloo"></a> <a href="https://github.com/chkpnt"><img src="https://avatars.githubusercontent.com/u/1956979?s=50&v=4" width="50" title="Gregor Dschung" alt="Gregor Dschung"></a> <a href="https://github.com/daltonboll"><img src="https://avatars.githubusercontent.com/u/5821829?v=4" width="50" title="Dalton Boll" alt="daltonboll"></a>

↑ top | ↓ contents

⚙️ How the plugin works

The plugin resolves references in the HTML template and adds them to the Webpack compilation. Webpack will automatically process the source files, and the plugin replaces the references with their output filenames in the generated HTML. See how the plugin works under the hood.

<img width="830" style="max-width: 100%;" src="images/workflow.png">

❓Question / Feature Request / Bug

If you have discovered a bug or have a feature suggestion, feel free to create an issue on GitHub.

📚 Read it

<a id="whats-new" name="whats-new"></a>

🔆 What's New in v4

🔆 What's New in v3

🔆 What's New in v2

For full release notes see the changelog.

⚠️ Limitations

Cache type

The current version works stably with cache.type as 'memory' (Webpack's default setting).

Support for the 'filesystem' cache type is in beta. It works stably in standard use cases, but it cannot be guaranteed to work in all use cases. If you have any problems, feel free to create an issue.

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<a id="install" name="install"></a>

Install and Quick start

Install the html-bundler-webpack-plugin:

npm install html-bundler-webpack-plugin --save-dev

It's recommended to combine html-bundler-webpack-plugin with the css-loader and the sass-loader.
Install additional packages for styles:

npm install css-loader sass-loader sass --save-dev

Start with an HTML template. Add the <link> and <script> tags. You can include asset source files such as SCSS, JS, images, and other media files directly in an HTML template.

The plugin resolves <script src="..."> <link href="..."> and <img src="..." srcset="..."> that references your script, style and image source files.

For example, there is the template ./src/views/home.html:

<html>
  <head>
    <!-- variable from Webpack config -->
    <title><%= title %></title>
    <!-- relative path to favicon source file -->
    <link href="./favicon.ico" rel="icon" />
    <!-- relative path to SCSS source file -->
    <link href="./style.scss" rel="stylesheet" />
    <!-- relative path to JS source file -->
    <script src="./main.js" defer="defer"></script>
  </head>
  <body>
    <h1>Hello World!</h1>
    <!-- relative path to image source file -->
    <img src="./picture.png" />
  </body>
</html>

All source filenames should be relative to the entrypoint template, or you can use Webpack alias. The references are rewritten in the generated HTML so that they point to the correct output files.

The generated HTML contains URLs of the output filenames:

<html>
  <head>
    <title>Homepage</title>
    <link href="img/favicon.3bd858b4.ico" rel="icon" />
    <link href="css/style.05e4dd86.css" rel="stylesheet" />
    <script src="js/main.f4b855d8.js" defer="defer"></script>
  </head>
  <body>
    <h1>Hello World!</h1>
    <img src="img/picture.58b43bd8.png" />
  </body>
</html>

<a id="simple-webpack-config" name="simple-webpack-config"></a>

Pages can be defined in the entry option. JS and CSS can be configured using the js and css options.

If the entry option is a path, the plugin finds all templates automatically and keep the same directory structure in the output directory.

If the entry option is an object, the key is an output filename without .html extension and the value is a template file.

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');

module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      // automatically processing all templates in the path
      entry: 'src/views/',
      
      // - OR - define pages manually (key is output filename w/o `.html`)
      entry: {
        index: 'src/views/home.html', // => dist/index.html
        'news/sport': 'src/views/news/sport/index.html', // => dist/news/sport.html
      },
      
      // - OR - define pages with variables
      entry: [
        {
          import: 'src/views/home.html', // template file
          filename: 'index.html', // => dist/index.html
          data: { title: 'Homepage' }, // pass variables into template
        },
        {
          import: 'src/views/news/sport/index.html', // template file
          filename: 'news/sport.html', // => dist/news/sport.html
          data: { title: 'Sport news' }, // pass variables into template
        },
      ],
      
      // - OR - combine both the pages with and w/o variables in one entry
      entry: {
        // simple page config w/o variables
        index: 'src/views/home.html', // => dist/index.html
        // advanced page config with variables
        'news/sport': { // => dist/news/sport.html
          import: 'src/views/home.html', // template file
          data: { title: 'Sport news' }, // pass variables into template
        },
      },

      js: {
        // JS output filename, used if `inline` option is false (defaults)
        filename: 'js/[name].[contenthash:8].js',
        //inline: true, // inlines JS into HTML
      },
      css: {
        // CSS output filename, used if `inline` option is false (defaults)
        filename: 'css/[name].[contenthash:8].css',
        //inline: true, // inlines CSS into HTML
      },
    }),
  ],
  module: {
    rules: [
      {
        test: /\.(css|sass|scss)$/,
        use: ['css-loader', 'sass-loader'],
      },
      {
        test: /\.(ico|png|jp?g|webp|svg)$/,
        type: 'asset/resource',
        generator: {
          filename: 'img/[name].[hash:8][ext][query]',
        },
      },
    ],
  },
};

ℹ️ Note

To define the JS output filename, use the js.filename option of the plugin.
Don't use Webpack's output.filename, hold all relevant settings in one place - in plugin options.
Both places have the same effect, but js.filename has priority over output.filename.

For splitChunks see How to configure splitChunks.

No additional template loader is required. The plugin handles templates with base EJS-like syntax automatically. The default templating engine is Eta.

For using the native EJS syntax see Templating with EJS.
For using the Handlebars see Templating with Handlebars.
For other templates see Template engines.

For custom templates, you can use the preprocessor option to handle any template engine.

<table> <tr> <td>Simple example SPA</td> <td>

Open in StackBlitz

</td> </tr> <tr> <td>Automatically processing many HTML templates</td> <td>

Open in StackBlitz

</td> </tr> <tr> <td>Create multiple HTML pages</td> <td>

See boilerplate

</td> </tr> </table>

↑ top

<a id="contents" name="contents"></a>

Table of Contents

  1. Features
  2. Install and Quick start
  3. Webpack options
  4. Build-in Plugins
  5. Third-party Plugins
  6. Hooks & Callbacks
  7. Plugin options
  8. Loader options
  9. Using template engines
  10. Using template in JavaScript
  11. Setup Live Reload
  12. Recipes
  13. Problems & Solutions
  14. <a id="demo-sites" name="demo-sites"></a> Demo sites
  15. <a id="usage-examples" name="usage-examples"></a> Usage examples

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<a id="features" name="features"></a>

Features

<a id="note-asset-source" name="note-asset-source"></a> (*) - asset/source works currently for SVG only, in a next version will work for other files too

<a id="list-of-plugins" name="list-of-plugins"></a>

Why do many developers switch from Webpack to other bundlers?

One of the reasons they cite is the complex configuration many different plugins and loaders for one simple thing - rendering an HTML page with assets.

The HTML bundler plugin "changes the rule of the game", making configuration very simple and clear. Just one plugin replaces the functionality of the plugins and loaders:

PackageFeatures
html-webpack-plugincreates HTML and inject script tag for compiled JS file into HTML
mini-css-extract-plugininjects link tag for processed CSS file into HTML
webpack-remove-empty-scriptsremoves generated empty JS files
html-loaderexports HTML, resolving attributes
style-loaderinjects an inline CSS into HTML
html-webpack-inject-preloadinject preload link tags
preload-webpack-plugininject preload link tags
html-webpack-inline-source-plugininline JS and CSS into HTML
html-inline-css-webpack-plugininline CSS into HTML
posthtml-inline-svginjects an inline SVG icon into HTML
resolve-url-loaderresolves a relative URL in CSS
svg-url-loaderencodes a SVG data-URL as utf8
webpack-subresource-integrity enables Subresource Integrity
favicons-webpack-plugin generates favicons and icons
handlebars-webpack-pluginrenders Handlebars templates
handlebars-loadercompiles Handlebars templates
pug-loadercompiles Pug templates
nunjucks-loadercompiles Nunjucks templates

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<a id="webpack-options" name="webpack-options"></a>

Webpack options

Important Webpack options used to properly configure this plugin.

<a id="webpack-option-output" name="webpack-options-output"></a> <a id="webpack-option-output-path" name="webpack-options-output-path"></a>

output.path

Type: string Default: path.join(process.cwd(), 'dist')

The root output directory for all processed files, as an absolute path.
You can omit this option, then all generated files will be saved under dist/ in your project directory.

<a id="webpack-option-output-publicpath" name="webpack-options-output-publicpath"></a>

output.publicPath

Type: string|function Default: auto

The value of the option is prefixed to every URL created by this plugin. If the value is not the empty string or auto, then the option must end with /.

The possible values:

<a id="webpack-option-output-filename" name="webpack-options-output-filename"></a>

output.filename

Type: string|function Default: [name].js

The output name of a generated JS file.
Highly recommended to define the filename in the Plugin option js.filename.

The output name of a generated CSS file is determined in the Plugin option css.filename.

Define output JS and CSS filenames in the Plugin option, in one place:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');
module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      js: {
        // define the output name of a generated JS file here
        filename: 'js/[name].[contenthash:8].js',
      },
      css: {
        // define the output name of a generated CSS file here
        filename: 'css/[name].[contenthash:8].css',
      },
    }),
  ],
};

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<a id="webpack-option-entry" name="webpack-options-entry"></a>

entry

The starting point to build the bundle.

ℹ️ Note

Using this plugin an entry point is an HTML template. All script and style source files must be specified in the HTML template.

You can use the Webpack entry option to define HTML templates, but it is highly recommended to define all templates in plugin option entry, because it has an additional data property (not available in the Webpack entry) to pass custom variables into the HTML template.

For details see the plugin option entry.

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<a id="build-in-plugins" name="build-in-plugins"></a>

Build-in Plugins

There are the most useful plugins available "out of the box". The build-in plugins maintained by the HtmlBundlerPlugin.

All build-in plugins are in the /plugins subdirectory of the HtmlBundlerPlugin.

FaviconsBundlerPlugin

<a id="favicons-bundler-plugin" name="favicons-bundler-plugin"></a>

The FaviconsBundlerPlugin generates favicons for different devices and injects favicon tags into HTML head.

Install

This plugin requires the additional favicons package.

npm install favicons -D

Config

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');
const { FaviconsBundlerPlugin } = require('html-bundler-webpack-plugin/plugins');

module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        // source favicon file must be specified directly in HTML using link tag
        index: './src/views/index.html',
      },
    }),
    // add the favicons plugin
    new FaviconsBundlerPlugin({
      enabled: 'auto', // true, false, auto - generate favicons in production mode only
      // favicons configuration options, see https://github.com/itgalaxy/favicons#usage
      faviconOptions: {
        path: '/img/favicons', // favicons output path relative to webpack output.path
        icons: {
          android: true, // Create Android homescreen icon.
          appleIcon: true, // Create Apple touch icons.
          appleStartup: false, // Create Apple startup images.
          favicons: true, // Create regular favicons.
          windows: false, // Create Windows 8 tile icons.
          yandex: false, // Create Yandex browser icon.
        },
      },
    }),
  ],
  module: {
    rules: [
      {
        test: /\.(png|jpe?g|ico|svg)$/,
        type: 'asset/resource',
      },
    ],
  },
};

FaviconsBundlerPlugin options

Usage

The source file of your favicon must be specified directly in HTML as the link tag with rel="icon" attribute.

If the FaviconsBundlerPlugin is disabled or as auto in development mode, then the source favicon file will be processed via webpack.

If the FaviconsBundlerPlugin is enabled or as auto in production mode, then the source favicon file will be processed via favicons module and the original link tag with favicon will be replaced with generated favicon tags.

For example, there is the src/views/index.html

<!DOCTYPE html>
<html>
<head>
  <!-- source favicon file relative to this HTML file, or use a webpack alias -->
  <link href="./myFavicon.png" rel="icon" />
</head>
<body>
  <h1>Hello World!</h1>
</body>
</html>

The generated HTML when FaviconsBundlerPlugin is disabled:

<!DOCTYPE html>
<html>
<head>
  <!-- output favicon file -->
  <link href="assets/img/myFavicon.1234abcd.png" rel="icon" />
</head>
<body>
  <h1>Hello World!</h1>
</body>
</html>

The generated HTML when FaviconsBundlerPlugin is enabled:

<!DOCTYPE html>
<html>
<head>
  <!-- original tag is replaced with tags generated by favicons module -->
  <link rel="apple-touch-icon" sizes="1024x1024" href="/img/favicons/apple-touch-icon-1024x1024.png">
  <link rel="apple-touch-icon" sizes="114x114" href="/img/favicons/apple-touch-icon-114x114.png">
  <link rel="apple-touch-icon" sizes="120x120" href="/img/favicons/apple-touch-icon-120x120.png">
  <link rel="apple-touch-icon" sizes="144x144" href="/img/favicons/apple-touch-icon-144x144.png">
  <link rel="apple-touch-icon" sizes="152x152" href="/img/favicons/apple-touch-icon-152x152.png">
  <link rel="apple-touch-icon" sizes="167x167" href="/img/favicons/apple-touch-icon-167x167.png">
  <link rel="apple-touch-icon" sizes="180x180" href="/img/favicons/apple-touch-icon-180x180.png">
  <link rel="apple-touch-icon" sizes="57x57" href="/img/favicons/apple-touch-icon-57x57.png">
  <link rel="apple-touch-icon" sizes="60x60" href="/img/favicons/apple-touch-icon-60x60.png">
  <link rel="apple-touch-icon" sizes="72x72" href="/img/favicons/apple-touch-icon-72x72.png">
  <link rel="apple-touch-icon" sizes="76x76" href="/img/favicons/apple-touch-icon-76x76.png">
  <link rel="icon" type="image/png" sizes="16x16" href="/img/favicons/favicon-16x16.png">
  <link rel="icon" type="image/png" sizes="32x32" href="/img/favicons/favicon-32x32.png">
  <link rel="icon" type="image/png" sizes="48x48" href="/img/favicons/favicon-48x48.png">
  <link rel="icon" type="image/x-icon" href="/img/favicons/favicon.ico">
  <link rel="manifest" href="/img/favicons/manifest.webmanifest">
  <meta name="apple-mobile-web-app-capable" content="yes">
  <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
  <meta name="apple-mobile-web-app-title" content="My App">
  <meta name="application-name" content="My App">
  <meta name="mobile-web-app-capable" content="yes">
  <meta name="theme-color" content="#fff">
</head>
<body>
  <h1>Hello World!</h1>
</body>
</html>

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<a id="third-party-plugins" name="third-party-plugins"></a>

Third-party Plugins

The third-party plugins not maintained by the HtmlBundlerPlugin. It potentially does not have the same support, security policy or license as Build-in Plugins.

You can create own plugin using the plugin hooks. As a reference plugin, you can use the FaviconsBundlerPlugin.

If you have a useful plugin, create a PR with the link to you plugin.

The plugin name must end with -bundler-plugin, e.g. hello-world-bundler-plugin.

Currently there are no plugins yet. Be the first to create one.

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<a id="plugin-hooks-and-callbacks" name="plugin-hooks-and-callbacks"></a>

Hooks & Callbacks

Using hooks and callbacks, you can extend the functionality of this plugin.

The hook can be defined in an external plugin. The callback is defined as an option in the HTMLBundlerPlugin.

Most hooks have a callback with the same name. Each callback is called after hook with the same name. So with a callback, you can change the result of the hook.

When using callbacks

If you have small code just for your project or are doing debugging, you can use callbacks.

When using hooks

Using hooks you can create your own plugin.

How the plugin works under the hood.

<center> <img width="765" style="max-width: 100%;" src="images/hooks.png" alt="HTMLBundlerPlugin hooks & callbacks"> </center>

How to use hooks

The simplest way, add the { apply() { ... } } object to the array of the Webpack plugins:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');

module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        index: './src/index.html',
      },
    }),
    // your plugin
    {
      apply(compiler) {
        const pluginName = 'MyPlugin';

        compiler.hooks.compilation.tap(pluginName, (compilation) => {
          const hooks = HtmlBundlerPlugin.getHooks(compilation);

          // modify generated HTML of the index.html template
          hooks.beforeEmit.tap(pluginName, (content, { name, sourceFile, assetFile }) => {
            return content.replace('something...', 'other...')
          });
        });
      },
    },
  ],
};

You can use this template as the basis for your own plugin:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');

class MyPlugin {
  pluginName = 'my-plugin';
  options = {};

  /**
   * @param {{ enabled: boolean | 'auto'}} options The options of your plugin.
   */
  constructor(options = {}) {
    this.options = options;
  }

  apply(compiler) {
    // you can use the API of the HtmlBundlerPlugin.option
    const enabled = HtmlBundlerPlugin.option.toBool(this.options?.enabled, true, 'auto');
    const outputPath = HtmlBundlerPlugin.option.getWebpackOutputPath();

    if (!enabled) {
      return;
    }

    const { pluginName } = this;
    const { webpack } = compiler; // instance of the Webpack
    const fs = compiler.inputFileSystem.fileSystem; // instance of the Webpack FyleSystem

    // start your plugin from the webpack compilation hook
    compiler.hooks.compilation.tap(pluginName, (compilation) => {
      const hooks = HtmlBundlerPlugin.getHooks(compilation);
      
      // usage of the sync, async and promise hooks

      // sync hook
      hooks.<hookName>.tap(pluginName, (...arguments) => {
        // do somthing here ...
        const result = 'your result';
        // return the result
        return result;
      });
      
      // async hook
      hooks.<hookName>.tapAsync(pluginName, (...arguments, callback) => {
        // do somthing here ...
        const result = 'your result';
        // call the callback function to resolve the async hook
        callback(result);
      });
      
      // promise hook
      hooks.<hookName>.tapPromise(pluginName, (...arguments) => {
        // do somthing here ...
        const result = 'your result';
        // return the promise with the result
        return Promise.resolve(result);
      });
    });
  }
}

module.exports = MyPlugin;

Then add your plugin in the webpack config:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');
const MyBundlerPlugin = require('my-bundler-plugin');

module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        index: './src/index.html',
      },
    }),
    // your plugin
    new MyBundlerPlugin({ enabled: true });
  ],
};

For an example implementation see FaviconsBundlerPlugin.

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<a id="hook-beforePreprocessor" name="hook-beforePreprocessor"></a>

beforePreprocessor

AsyncSeriesWaterfallHook<[
  content: string,
  loaderContext: LoaderContext<Object> & { data: { [key: string]: any } | string }
]>;

For details on AsyncSeriesWaterfallHook see the hook interface.

For details on hook parameters, see in the beforePreprocessor callback option.

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<a id="hook-preprocessor" name="hook-preprocessor"></a>

preprocessor

AsyncSeriesWaterfallHook<[
  content: string,
  loaderContext: LoaderContext<Object> & { data: { [key: string]: any } | string }
]>;

For details on AsyncSeriesWaterfallHook see the hook interface.

For details on hook parameters, see in the preprocessor callback option.

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<a id="hook-resolveSource" name="hook-resolveSource"></a>

resolveSource

SyncWaterfallHook<[
  source: string,
  info: {
    type: 'style' | 'script' | 'asset';
    tag: string;
    attribute: string;
    value: string;
    resolvedFile: string;
    issuer: string
  },
]>;

no calback

Called after resolving of a source attribute defined by source loader option.

For details on SyncWaterfallHook see the hook interface.

Hook parameters:

Return a string to override the resolved value of the attribute or undefined to keep the resolved value.

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<a id="hook-postprocess" name="hook-postprocess"></a>

postprocess

AsyncSeriesWaterfallHook<[content: string, info: TemplateInfo]>;

For details on AsyncSeriesWaterfallHook see the hook interface.

For details on hook parameters, see in the postprocess callback option.

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<a id="hook-beforeEmit" name="hook-beforeEmit"></a>

beforeEmit

AsyncSeriesWaterfallHook<[content: string, entry: CompileEntry]>;

For details on AsyncSeriesWaterfallHook see the hook interface.

For details on hook parameters, see in the beforeEmit callback option.

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<a id="hook-afterEmit" name="hook-afterEmit"></a>

afterEmit

AsyncSeriesHook<[entries: CompileEntries]>;

For details on AsyncSeriesHook see the hook interface.

For details on hook parameters, see in the afterEmit callback option.

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<a id="hook-integrity-hashes" name="hook-integrity-hashes"></a>

integrityHashes

AsyncSeriesHook<{
  // the map of the output asset filename to its integrity hash
  hashes: Map<string, string>;
}>;

Called after all assets have been processed and hashes have finite values and cannot be changed, at the afterEmit stage. This can be used to retrieve the integrity values for the asset files.

For details on AsyncSeriesHook see the hook interface.

Callback Parameter: hashes is the map of the output asset filename to its integrity hash. The map only contains JS and CSS assets that have a hash.

You can write your own plugin, for example, to extract integrity values into the separate file:

const fs = require('fs');
const path = require('path');
const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');
module.exports = {
  output: {
    crossOriginLoading: 'anonymous', // required for Subresource Integrity
  },
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        index: './src/index.html',
      },
      js: {
        filename: '[name].[contenthash:8].js',
        chunkFilename: '[name].[contenthash:8].chunk.js',
      },
      css: {
        filename: '[name].[contenthash:8].css',
        chunkFilename: '[name].[contenthash:8].chunk.css',
      },
      integrity: 'auto',
    }),
    // your plugin to extract the integrity values
    {
      apply(compiler) {
        compiler.hooks.compilation.tap('MyPlugin', (compilation) => {
          const hooks = HtmlBundlerPlugin.getHooks(compilation);
          hooks.integrityHashes.tapAsync(
            'MyPlugin', 
            (hashes) => Promise.resolve().then(() => {
                if (hashes.size > 0) {
                  const saveAs = path.join(__dirname, 'dist/integrity.json');
                  const json = Object.fromEntries(hashes);
                  fs.writeFileSync(saveAs, JSON.stringify(json, null, '  ')); // => save to file
                  console.log(hashes); // => output to console
                }
              })
            );
          }
        );
      },
    },
  ],
};

The content of the dist/integrity.json file looks like:

{
  "815.49b3d882.chunk.js": "sha384-dBK6nNrKKk2KjQLYmHZu6tuWwp7kBzzEvdX+4Ni11UzxO2VHvP4A22E/+mmeduul",
  "main.9c043cce.js": "sha384-AbfLh7mk6gCp0nhkXlAnOIzaHeJSB8fcV1/wT/FWBHIDV7Blg9A0sukZ4nS3xjtR"
  "main.dc4ea4af.chunk.css": "sha384-W/pO0vwqqWBj4lq8nfe+kjrP8Z78smCBttkCvx1SYKrVI4WEdJa6W6i0I2hoc1t7",
  "style.47f4da55.css": "sha384-gaDmgJjLpipN1Jmuc98geFnDjVqWn1fixlG0Ab90qFyUIJ4ARXlKBsMGumxTSu7E",
}

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<a id="plugin-options" name="plugin-options"></a>

Plugin options

<a id="option-test" name="option-test"></a>

test

Type: RegExp Default: /\.(html|eta)$/

The test option allows to handel only those templates as entry points that match the name of the source file.

For example, if you have other templates, e.g. *.liquid, as entry points, then you can set the option to match custom template files: test: /\.(html|liquid)$/.

The test value is used in the default loader.

ℹ️ Note

Using the preprocessor options will be added the templating engine extensions in the test automatically. Defaults preprocessor is Eta therefore is used the /\.(html|eta)$/ RegExp.

For example, if you define the preprocessor option as the handlebars, then will be used the /\.(html|hbs|handlebars)$/ RegExp automatically.

Why is it necessary to define it? Can't it be automatically processed?

This plugin is very powerful and has many experimental features not yet documented. One of the next features will be the processing scripts and styles as entry points for library bundles without templates. To do this, the plugin must differentiate between a template entry point and a script/style entry point. This plugin can completely replace the functionality of mini-css-extract-plugin and webpack-remove-empty-scripts in future.

<a id="option-entry" name="option-entry"></a>

entry

Type: EntryObject | Array<EntryDescription> | string.

The EntryObject is identical to Webpack entry plus additional data property to pass custom variables into the HTML template.

Defines the entry points for HTML files. You can specify a path to a template directory to automatically process all templates, or specify multiple entries if you want to manually manage templates files.

ℹ️ Note

You can define templates both in Webpack entry and in the entry option of the plugin. The syntax is identical. But the data property can only be used in the entry option of the plugin.

💡 Tip

Specify template files as entry points in the entry plugin option.

An HTML template is a starting point for collecting all the dependencies used in your web application. Specify source scripts (JS, TS) and styles (CSS, SCSS, LESS, etc.) directly in HTML. The plugin automatically extracts JS and CSS whose source files are specified in an HTML template.

type EntryObject = {
  [name: string]: EntryDescription | string;
};

The key of the EntryObject is the output filename without an extension, relative to the outputPath option.

Simple syntax

When the entry point value is a string, it must be an absolute or relative template file. For example:

{
  entry: {
    index: path.join(__dirname, 'src/views/home/index.html'), // => dist/index.html
    'news/sport': 'src/views/news/sport/index.html', // => dist/news/sport.html
  },
}

<a id="option-entry-advanced" name="option-entry-advanced"></a>

Advanced syntax

If you need to pass data to a template or want to dynamically generate an output filename regardless of the entry key, you can define the value of an entry as an EntryDescription object.

type EntryDescription = {
  /**
   * Template file, relative of context or absolute.
   */
  import: string;
  /**
   * Specifies the filename of the output file.
   */
  filename?: FilenameTemplate;
  /**
   * The template data.
   */
  data?: { [key: string]: any } | string;
};

type FilenameTemplate =
  | string
  | ((pathData: import('webpack/Compilation').PathData, assetInfo?: import('webpack/Compilation').AssetInfo) => string);
import

The import is a path to a template file, absolute or relative to the Webpack context option.

filename

When the filename is defined as a string, it will be used as the output html filename. In this case, the entry key can be any unique string.

For example:

{
  entry: {
    page01: {
      import: 'src/views/news/sport/index.html', // <= source template
      filename: 'news/sport.html', // => output ./dist/news/sport.html
    },
  },
}

When the filename is defined as a template string, then the entry key will be used as the [name] in the template string. Defaults, the filename is the [name].html template string.

For example:

{
  entry: {
    'news/sport': {
      import: 'src/views/news/sport/index.html', // <= source template
      filename: '[name].html', // => output ./dist/news/sport.html
    },
  },
}

The example above is equivalent to the simple syntax:

{
  entry: {
    'news/sport': 'src/views/news/sport/index.html',
  },
}

<a id="option-entry-data" name="option-entry-data"></a>

data

The data is passed into preprocessor to render the template with variables.

<a id="option-entry-data-object" name="option-entry-data-object"></a> data as object

When the data is an object, it will be loaded once with Webpack start. After changing the data, you need to restart Webpack.

For example:

{
  entry: {
    index: {
      import: 'src/views/index.html',
      // pass data as an object
      data: {
        title: 'Home',
      }
    },
}

<a id="option-entry-data-json" name="option-entry-data-json"></a> data as JSON file

When the data is a string, it must be an absolute or relative path to a file. The file can be a JSON file or a JS file that exports the data as an object. Use the data as a file if you want to get dynamic data in a template. The data file will be reloaded after changes, without restarting Webpack.

For example, using *.json data file:

{
  entry: {
    index: {
      import: 'src/views/index.html',
      // load data from JSON file
      data: 'src/data/home.json',
    },
  },
}

The data file src/data/home.json:

{
  "title": "Home"
}

<a id="option-entry-data-js" name="option-entry-data-js"></a> data as JS file

To load data into a template dynamically you can use JS file. In JS file you can load data from a database.

For example, using *.js data file:

{
  entry: {
    index: {
      import: 'src/views/index.html',
      // load data from JS file
      data: 'src/data/home.js',
    },
  },
}

The data file src/data/home.js:

// here you can load data from a database
const data = {
  title: 'Home',
};

module.exports = data;

💡 Tip

To pass global variables in all templates use the data plugin option.

<a id="option-entry-array" name="option-entry-array"></a>

Entry as an array

If the entry is the array of the EntryDescription then the filename property is required.

{
  entry: [
    {
      filename: 'index.html', // => output filename dist/index.html
      import: 'src/views/index.html', // template file
      data: { title: 'Homepage' }, // page specifically variables
    },
    {
      filename: 'about.html',
      import: 'src/views/about.html',
      data: { title: 'About' },
    },
    {
      filename: 'news/sport.html',
      import: 'src/views/news/sport.html',
      data: { title: 'Sport' },
    },
  ],
}

<a id="option-entry-object" name="option-entry-object"></a>

Entry as an object

The absolute equivalent to the example above using an object is:

{
  entry: {
    index: { // => output filename dist/index.html
      import: 'src/views/index.html', // template file
      data: { title: 'Homepage' }, // page specifically variables
    },
    about: {
      import: 'src/views/about.html',
      data: { title: 'About' },
    },
    'news/sport': {
      import: 'src/views/news/sport.html',
      data: { title: 'Sport' },
    },
  },
}

The difference between object and array notation:

<a id="option-entry-path" name="option-entry-path"></a>

Entry as a path to templates

You can define the entry as a path to recursively detect all templates from that directory.

When the value of the entry is a string, it must be an absolute or relative path to the templates' directory. Templates matching the test option are detected recursively from the path. The output files will have the same folder structure as source template directory.

For example, there are files in the template directory ./src/views/

./src/views/index.html
./src/views/about/index.html
./src/views/news/sport/index.html
./src/views/news/sport/script.js
./src/views/news/sport/style.scss
...

Define the entry option as the relative path to pages:

new HtmlBundlerPlugin({
  entry: 'src/views/',
});

Files that are not matching to the test option are ignored. The output HTML filenames keep their source structure in the output directory relative to the entry path:

./dist/index.html
./dist/about/index.html
./dist/news/sport/index.html
...

If you need to modify the output HTML filename, use the filename option as the function.

For example, we want keep a source structure for all pages, while ./src/views/home/index.html should not be saved as ./dist/home/index.htm, but as ./dist/index.htm:

new HtmlBundlerPlugin({
  // path to templates
  entry: 'src/views/',

  filename: ({ filename, chunk: { name } }) => {
    // transform 'home/index' filename to output file 'index.html'
    if (name === 'home/index') {
      return 'index.html'; // save as index.html in output directory
    }
    // bypass the original structure
    return '[name].html';
  },
});

ℹ️ Note

In serve/watch mode, you can add/delete/rename a template file in the entry path without restarting Webpack.

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<a id="option-entry-filter" name="option-entry-filter"></a>

entryFilter

Filter to process only matching template files. This option works only if the entry option is a path.

Type:

type entryFilter = 
  | RegExp
  | Array<RegExp>
  | { includes?: Array<RegExp>; excludes?: Array<RegExp> }
  | ((file: string) => void | false);

Default value:

{
  includes: [
    /\.(html|eta)$/,
  ], 
  excludes: [] 
}

The default includes property depends on the used preprocessor option. Each preprocessor has its own filter to include from the entry path only relevant template files.

entryFilter as RegExp

The filter works as include only files that match the regular expressions. For example:

new HtmlBundlerPlugin({
  entry: 'src/views/pages/',
  entryFilter: /index\.html$/, // render only `index.html` files in all sub dirs
})

entryFilter as Array<RegExp>

The filter works as include only files that match one of the regular expressions. For example:

new HtmlBundlerPlugin({
  entry: 'src/views/pages/',
  entryFilter: [
    // render only page specifically files, e.g.: `index.html`, `contact.html`, `about.html`
    /index\.html$/,
    /contact\.html$/,
    /about\.html$/,
  ],
})

entryFilter as { includes: Array<RegExp>, excludes: Array<RegExp> }

The filter includes only files that match one of the regular expressions, except excluded files. For example:

new HtmlBundlerPlugin({
  entry: 'src/views/pages/',
  entryFilter: {
    includes: [/\.(html|eta)$/,], // render all `.html` and `.eta` template files
    excludes: [/partial/],  // except partial files
  },
})

entryFilter as callback

In addition to the default includes filter, this filter works as exclude a file if it returns false. If the callback returns true or nothing, then the file will be processed.

For example:

new HtmlBundlerPlugin({
  entry: 'src/views/pages/',
  entryFilter: (file) => {
    if (/partial/.test(file)) return false; // ignore files containing the `partial` in the path
  },
})

The file argument is the absolute path of a template file.

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<a id="option-outputpath" name="option-outputpath"></a>

outputPath

Type: string Default: webpack output.path

The output directory for generated HTML files only. This directory can be absolute or relative to webpack output.path.

For example, here are html and js files:

src/index.html
src/main.js

src/index.html

<!doctype html>
<html>
  <head>
    <script src="./main.js"></script>
  </head>
  <body>
    <h1>Hello World!</h1>
  </body>
</html>

There is webpack config:

const path = require('path');
const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');
module.exports = {
  output: {
    path: path.join(__dirname, 'dist/'), // the root output directory for all assets
  },
  plugins: [
    new HtmlBundlerPlugin({
      // absoulte html output directory
      outputPath: path.join(__dirname, 'dist/example/'),
      // OR relative to output.path
      // outputPath: 'example/',
      entry: {
        index: './src/index.html', // => dist/example/index.html
      },
      js: {
        filename: '[name].bundle.js',
        outputPath: 'assets/js/', // output path for js files, relative to output.path
      },
    }),
  ],
};

The processed files in the output directory:

dist/example/index.html
dist/assets/js/main.bundle.js

The generated dist/example/index.html:

<!doctype html>
<html>
  <head>
    <script src="../assets/js/main.bundle.js"></script>
  </head>
  <body>
    <h1>Hello World!</h1>
  </body>
</html>

⚠️ Warning

The outputPath is NOT used for output assets (js, css, images, etc.).

<a id="option-filename" name="option-filename"></a>

filename

Type: string | Function Default: [name].html

The HTML output filename relative to the outputPath option.

If type is string then following substitutions (see output.filename for chunk-level) are available in template string:

If type is Function then following arguments are available in the function:

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<a id="option-js" name="option-js"></a>

js

Type:

type JsOptions = {
  filename?: FilenameTemplate;
  chunkFilename?: FilenameTemplate;
  outputPath?: string;
  inline?: 'auto' | boolean | JsInlineOptions;
};

type JsInlineOptions = {
  enabled?: 'auto' | boolean;
  chunk?: RegExp | Array<RegExp>;
  source?: RegExp | Array<RegExp>;
  attributeFilter?: (props: {
    attribute: string;
    value: string;
    attributes: { [attributeName: string]: string };
  }) => boolean | void;
};

Default properties:

{
  filename: '[name].js',
  chunkFilename: '[id].js',
  outputPath: null,
  inline: false,
}

The inline property allows to inline compiled JavaScript chunks into HTML.

If inline is 'auto' or boolean, available values:

If inline is an object:

You can use both the chunk and the source options, then there will be inlined chunks matching regular expressions with OR logic.

For example, there is used the optimization.splitChunks and we want to inline only the small webpack runtime chunk but other JS chunks of the same split app.js file should be saved to chunk files, then use the following inline option:

js: {
  filename: 'js/[name].[contenthash:8].js',
  inline: {
    chunk: [/runtime.+[.]js/],
  },
},

Then the app.js file will be split to many output chunks in the dist/ directory, e.g.:

js/325.xxxxxxxx.js  -> save as file
js/545.xxxxxxxx.js  -> save as file
js/app.xxxxxxxx.js  -> save as file
runtime.xxxxxxxx.js        -> inline the chunk into HTML and NOT save as file

The single runtime.xxxxxxxx.js chunk will be injected into HTML, other chunks will be saved to output directory.

ℹ️ Note

The filename and chunkFilename options are the same as in Webpack output options, just defined in one place along with other relevant plugin options. You don't need to define them in the in Webpack output options anymore. Keep the config clean & clear.

To keep some original script tag attributes in the inlined script tag, use the attributeFilter. For example, there is a script tag with attributes:

<script id="js-main" src="./main.js" defer></script>

Use the attributeFilter:

new HtmlBundlerPlugin({
  // ...
  js: {
    inline: {
      attributeFilter: ({ attributes, attribute, value }) => {
        if (attribute === 'id') return true;
      },
    },
  },
}

The inlined tag contains the id attribute, but the src and defer are removed:

<script id="js-main">
  // inlined JavaScript code
</script>

All source script files specified in <script src="..."> are automatically resolved,
and JS will be extracted to output file. The source filename will be replaced with the output filename.

For example:

<script src="./main.js"></script>

The default JS output filename is [name].js. You can specify your own filename using webpack filename substitutions:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');
module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      js: {
        filename: 'js/[name].[contenthash:8].js',
      },
    }),
  ],
};

The [name] is the base filename script. For example, if source file is main.js, then output filename will be js/main.1234abcd.js.
If you want to have a different output filename, you can use the filename options as the function.

The chunkFilename option only takes effect if you have the optimization.splitChunks option.

For example:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');
module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        index: 'src/views/index.html',
      },
      js: {
        filename: 'js/[name].[contenthash:8].js',
        chunkFilename: 'js/[id].[contenthash:8].js',
      },
    }),
  ],
  optimization: {
    splitChunks: {
      cacheGroups: {
        scripts: {
          test: /\.(js|ts)$/, // <= IMPORTANT: split only script files
          chunks: 'all',
        },
      },
    },
  },
};

⚠️ Warning

Webpack tries to split and concatenate chunks of all files (templates, styles, scripts) into jumbles. Therefore, the test option MUST be specified to match only source JS files, otherwise Webpack will generate invalid output files.

Also see How to keep package name for split chunks from node_modules.

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<a id="option-css" name="option-css"></a>

css

Type:

type CssOptions = {
  test?: RegExp;
  filename?: FilenameTemplate;
  chunkFilename?: FilenameTemplate;
  outputPath?: string;
  inline?: 'auto' | boolean;
  hot?: boolean;
};

Default properties:

{
  test: /\.(css|scss|sass|less|styl)$/,
  filename: '[name].css',
  chunkFilename: '[name].css',
  outputPath: null,
  inline: false,
  hot: false,
}

All source style files specified in <link href="..." rel="stylesheet"> are automatically resolved, and CSS will be extracted to output file. The source filename will be replaced with the output filename.

For example:

<link href="./style.scss" rel="stylesheet" />

⚠️ Warning

Don't import source styles in JavaScript. Styles should be specified directly in HTML.
Don't define source JS files in Webpack entry. Scripts must be specified directly in HTML.

The default CSS output filename is [name].css. You can specify your own filename using webpack filename substitutions:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');
module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      css: {
        filename: 'css/[name].[contenthash:8].css',
      },
    }),
  ],
};

The [name] is the base filename of a loaded style. For example, if source file is style.scss, then output filename will be css/style.1234abcd.css.
If you want to have a different output filename, you can use the filename options as the function.

<a id="option-css-hot" name="option-css-hot"></a>

css.hot option

⚠️ Limitation

If you use the Live Reload configuration, then be sure to exclude the style files (CSS/SCSS) from watching, otherwise after changes a style file, a page will be full reloaded.

ℹ️ Note

If devServer is configured for HRM with styles, then after changing the styles defined in HTML, Live Reload will not work for them. You should then reload the browser self.

Configuration of devServer to enable HMR:

devServer: {
  static: {
    directory: path.join(__dirname, 'dist'),
  },
  watchFiles: {
    paths: ['src/**/*.(html|eta)'], // <= exclude *.s?css from watching
    options: {
      usePolling: true,
    },
  },
},

💡 Tip: to enable HMR for all style files without a full reload, import all those styles in one JS file.

⚠️ Warning

Don't use mini-css-extract-plugin because the bundler plugin extracts CSS much faster than other plugins.

Don't use resolve-url-loader because the bundler plugin resolves all URLs in CSS, including assets from node modules.

Don't use style-loader because the bundler plugin can auto inline CSS and HMR.

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<a id="option-data" name="option-data"></a>

data

Since the v2.5.0, the data plugin option is the reference to loaderOptions.data.

Now it is possible to define the data option directly in the plugin options to simplify the config.

The NEW syntactic "sugar":

new HtmlBundlerPlugin({
  entry: {
    index: './src/views/home.ejs',
  },
  // new reference to the loaderOptions.data
  data: {...},
}),

The old syntax is still valid and will never be deprecated:

new HtmlBundlerPlugin({
  entry: {
    index: './src/views/home.ejs',
  },
  loaderOptions: {
    // original option is under loaderOptions
    data: {...},
  },
}),

Please see the details below under the data loader options.

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<a id="option-before-preprocessor" name="option-before-preprocessor"></a>

beforePreprocessor

Reference to loaderOption.beforePreprocessor

The plugin option is the reference to loaderOptions.beforePreprocessor.

Type:

type BeforePreprocessor =
  | false
  | ((
      content: string,
      loaderContext: LoaderContext<Object> & { data: { [key: string]: any } | string }
    ) => string | undefined);

Default: false

The content is the raw content of a template.

The description of all loaderContext attributes see in the Webpack documentation.

Returns the modified template. If you are not changing the template, you should return undefined or not use return at all.

The callback function called right before the preprocessor. This can be useful when using one of the predefined preprocessors and modifying the raw template or the data passed to the template.

For example:

new HtmlBundlerPlugin({
  entry: {
    index: 'src/views/pages/',
  },
  data: {
    title: 'Welcome to [sitename] website',
  },
  beforePreprocessor: (content, { resourcePath, data }) => {
    let sitename = 'Homepage';
    if (resourcePath.includes('/about.html')) sitename = 'About';
    data.title = data.title.replace('[sitename]', sitename); // modify template data
    return content.replaceAll('{{old_var}}', '{{new_var}}'); // modify template content
  },
  preprocessor: 'handlebars', // use the templating engine
});

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<a id="option-preprocessor" name="option-preprocessor"></a>

preprocessor (callback or string) and preprocessorOptions

The plugin options are the references to loaderOptions.preprocessor and loaderOptions.preprocessorOptions.

Now it is possible to define these options directly in the plugin options to simplify the config.

The NEW syntactic "sugar":

new HtmlBundlerPlugin({
  entry: {
    index: './src/views/home.ejs',
  },
  // new references to options in the loaderOptions
  preprocessor: 'ejs',
  preprocessorOptions: {...},
}),

The old syntax is still valid and will never be deprecated:

new HtmlBundlerPlugin({
  entry: {
    index: './src/views/home.ejs',
  },
  loaderOptions: {
    // original options are under loaderOptions
    preprocessor: 'ejs',
    preprocessorOptions: {...},
  },
}),

Please see the details below under the preprocessor and the preprocessorOptions options.

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<a id="option-postprocess" name="option-postprocess"></a>

postprocess callback

Type:

type postprocess = (
  content: string,
  info: TemplateInfo,
  compilation: Compilation
) => string | undefined;

type TemplateInfo = {
  name: string;
  assetFile: string;
  sourceFile: string;
  resource: string;
  outputPath: string;
};

Default: null

Called after the template has been compiled, but not yet finalized, before injection of the split chunks and inline assets.

The postprocess have the following arguments:

The TemplateInfo have the following properties:

Return new content as a string. If return undefined, the result processed via Webpack plugin is ignored and will be saved a result processed via the loader.

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<a id="option-beforeEmit" name="option-beforeEmit"></a>

beforeEmit callback

Type:

type BeforeEmit = (
  content: string,
  entry: CompileEntry,
  compilation: Compilation
) => string | undefined;

type CompileEntry = TemplateInfo & {
  // assets used in html
  assets: Array<CompileAsset>;
};

Default: null

Called at the latest stage of the processAssets hook, before emitting. This is the latest stage where you can change the html before it will be saved on the disk.

Callback parameters:

Return new content as a string. If return undefined then content will not be changed.

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<a id="option-afterEmit" name="option-afterEmit"></a>

afterEmit callback

Type:

type AfterEmit = (
  entries: Array<CompileEntry>,
  compilation: Compilation
) => Promise<void> | void;

Default: null

Called after emitting assets to output directory. This callback can be useful to create a manifest file containing source and output filenames.

Callback parameters:

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<a id="option-renderStage" name="option-renderStage"></a>

renderStage

Type: null | number

Default: Compilation.PROCESS_ASSETS_STAGE_OPTIMIZE_TRANSFER - 1

The stage to render output HTML in the processAssets Webpack hook. The minimal possible stage for the rendering is PROCESS_ASSETS_STAGE_SUMMARIZE.

For example:

const path = require('path');
const Compilation = require('webpack/lib/Compilation');
const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');
const CompressionPlugin = require('compression-webpack-plugin');

module.exports = {
  mode: 'production',
  output: {
    path: path.join(__dirname, 'dist/'),
  },
  plugins: [
    new CompressionPlugin(),
    new HtmlBundlerPlugin({
      entry: {
        index: 'src/index.html',
      },
      // Ensures that the CompressionPlugin save the resulting HTML into the `*.html.gz` file
      // after the rendering process in the HtmlBundlerPlugin.
      renderStage: Compilation.PROCESS_ASSETS_STAGE_OPTIMIZE_HASH + 1,
    }),
  ],
};

[!TIP] To ensures that the rendering process will be run after all optimizations and after all other plugins set the renderStage: Infinity + 1.

[!CAUTION] Use this option only to order the sequence of asset processing across multiple plugins that use the same processAssets hook.

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<a id="option-preload" name="option-preload"></a>

preload

Type:

type Preload = Array<{
  test: RegExp;
  as?: string;
  rel?: string;
  type?: string;
  attributes?: { [attributeName: string]: string | boolean };
}>;

Default: null

Generates and injects preload tags <link rel="preload"> in the head before all link or script tags for all matching source assets resolved in templates and styles.

The descriptions of the properties:

If you define the attributes than you can write the as, rel and type properties in the attributes.

For example:

{
  test: /\.(ttf|woff2?)$/,
  attributes: { as: 'font', rel: 'prefetch', crossorigin: true },
},

Preload styles

preload: [
  {
    test: /\.(css|scss|less)$/,
    as: 'style',
  },
],

The generated preload tag like the following:

<link rel="preload" href="css/style.1f4faaff.css" as="style" />

Preload scripts

preload: [
  {
    test: /\.(js|ts)$/,
    as: 'script',
  },
],

The generated preload tag like the following:

<link rel="preload" href="js/main.c608b1cd.js" as="script" />

Preload images

To preload all images use the options:

preload: [
  {
    test: /\.(png|jpe?g|webp|svg)$/,
    as: 'image',
  },
],

The generated preload tags like the following:

<link rel="preload" href="img/apple.697ef306.png" as="image" type="image/png" />
<link rel="preload" href="img/lemon.3666c92d.svg" as="image" type="image/svg+xml" />

You can preload images with a URL query, e.g. image.png?size=640, using the media attribute:

preload: [
  {
    test: /\.(png|jpe?g|webp)\?.*size=480/,
    attributes: { as: 'image', media: '(max-width: 480px)' },
  },
  {
    test: /\.(png|jpe?g|webp)\?.*size=640/,
    attributes: { as: 'image', media: '(max-width: 640px)' },
  },
],

ℹ️ Note

The media attribute be useful when used responsive-loader.

Preload fonts

preload: [
  {
    test: /\.(ttf|woff2?)$/,
    attributes: { as: 'font', crossorigin: true },
  },
],

ℹ️ Note

Font preloading requires the crossorigin attribute to be set. See font preload.

Preload tags order

The generated preload tags are grouped by content type and sorted in the order of the specified preload options.

For example, there is an HTML template with specified source assets:

<html>
  <head>
    <script src="./main.js" defer></script>
    <link href="./style.scss" rel="stylesheet" />
  </head>
  <body>
    <img src="./apple.png" alt="apple" />
    <script src="./app.js"></script>
    <img src="./lemon.svg" alt="lemon" />
  </body>
</html>

Specify the order of preload tags:

preload: [
  // 1. preload images
  {
    test: /\.(png|jpe?g|webp|svg)$/,
    as: 'image',
  },
  // 2. preload styles
  {
    test: /\.(css|scss)$/,
    as: 'style',
  },
  // 3. preload scripts
  {
    test: /\.(js|ts)$/,
    as: 'script',
  },
],

The generated HTML contains the preload tags exactly in the order of preload options:

<html>
  <head>
    <!-- 1. preload images -->
    <link rel="preload" href="img/apple.697ef306.png" as="image" type="image/png" />
    <link rel="preload" href="img/lemon.3666c92d.svg" as="image" type="image/svg+xml" />
    <!-- 2. preload styles -->
    <link rel="preload" href="css/style.1f4faaff.css" as="style" />
    <!-- 3. preload scripts -->
    <link rel="preload" href="js/main.c608b1cd.js" as="script" />
    <link rel="preload" href="js/app.2c8d13ac.js" as="script" />

    <script src="js/main.c608b1cd.js" defer></script>
    <link href="css/style.1f4faaff.css" rel="stylesheet" />
  </head>
  <body>
    <img src="img/apple.697ef306.png" alt="apple" />
    <script src="js/app.2c8d13ac.js"></script>
    <img src="img/lemon.3666c92d.svg" alt="lemon" />
  </body>
</html>

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<a id="option-minify" name="option-minify"></a>

minify

Type: 'auto'|boolean|Object Default: false

For minification generated HTML is used the html-minifier-terser with the following default options:

{
  collapseWhitespace: true,
  keepClosingSlash: true,
  removeComments: true,
  removeRedundantAttributes: false, // prevents styling bug when input "type=text" is removed
  removeScriptTypeAttributes: true,
  removeStyleLinkTypeAttributes: true,
  useShortDoctype: true,
  minifyCSS: true,
  minifyJS: true,
}

Possible values:

<a id="option-minify-options" name="option-minify-options"></a>

minifyOptions

Type: Object Default: null

When the minify option is set to 'auto' or true, you can configure minification options using the minifyOptions.

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<a id="option-extract-comments" name="option-extract-comments"></a>

extractComments

Type: boolean Default: false

Whether comments shall be extracted to a separate file like the *.LICENSE.txt.

By default, the built-in Webpack plugin TerserWebpackPlugin extracts the license banner from node modules into a separate *.LICENSE.txt file, although this is usually not necessary.

Therefore, by default, the Bundler Plugin does not allow extracting comments. This has the same effect as explicitly defining the extractComments: false option of the TerserWebpackPlugin.

If you want to allow extraction of *.LICENSE.txt files, set this option to true.

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<a id="option-integrity" name="option-integrity"></a>

integrity

Type: 'auto'|boolean|IntegrityOptions Default: false

The subresource integrity hash is a cryptographic value of the integrity attribute that used by a browser to verify that the content of an asset has not been manipulated. If the asset has been manipulated, the browser will never load it.

The Bundler Plugin generates the integrity hashes and adds the integrity attribute to the link and script tags when generating HTML.

No additional plugins required. This plugin computes integrity hashes itself.

type IntegrityOptions = {
  enabled?: 'auto' | boolean;
  hashFunctions?: HashFunctions | Array<HashFunctions>;
};
type HashFunctions = 'sha256' | 'sha384' | 'sha512';

If the integrity option is an object, then default options are:

{
  enabled: 'auto',
  hashFunctions: 'sha384',
}

ℹ️ Note

The W3C recommends using the SHA-384 hash algorithm.

The integrity or integrity.enabled has one of values:

The hashFunctions option can be a string to specify a single hash function name, or an array to specify multiple hash functions for compatibility with many browsers.

⚠️ Warning

When used the integrity option:

This requirement is necessary to avoid the case where the browser tries to load a contents of a file from the local cache since the filename has not changed, but the integrity value has changed on the server. In this case, the browser will not load the file because the integrity of the cached file computed by the browser will not match the integrity attribute computed on the server.

Add the integrity option in the Webpack config:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');

module.exports = {
  output: {
    // required for `integrity` to work in the browser
    crossOriginLoading: 'anonymous',
  },
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        index: 'src/views/index.html', // template where are included link and script tags
      },
      js: {
        filename: '[name].[contenthash:8].js', // the filename must contains a contenthash
      },
      css: {
        filename: '[name].[contenthash:8].js', // the filename must contains a contenthash
      },
      integrity: 'auto', // enable in `production`, disable in `development` mode
    }),
  ],
};

The source HTML template src/views/index.html:

<html>
  <head>
    <!-- include source style -->
    <link href="./style.scss" rel="stylesheet" />
    <!-- include source script -->
    <script src="./main.js" defer="defer"></script>
  </head>
  <body>
    <h1>Hello World!</h1>
  </body>
</html>

The generated HTML contains the integrity hashes:

<html>
  <head>
    <link
      href="style.1234abcd.css"
      rel="stylesheet"
      integrity="sha384-gaDmgJjLpipN1Jmuc98geFnDjVqWn1fixlG0Ab90qFyUIJ4ARXlKBsMGumxTSu7E"
      crossorigin="anonymous" />

    <script
      src="main.abcd1234.js"
      defer="defer"
      integrity="sha384-E4IoJ3Xutt/6tUVDjvtPwDTTlCfU5oG199UoqWShFCNx6mb4tdpcPLu7sLzNc8Pe"
      crossorigin="anonymous"></script>
  </head>
  <body>
    <h1>Hello World!</h1>
  </body>
</html>

integrityHashes hook

For details see the integrityHashes hook.

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<a id="option-watch-files" name="option-watch-files"></a>

watchFiles

Type:

type WatchFiles = {
  paths?: Array<string>;
  includes?: Array<RegExp>;
  excludes?: Array<RegExp>;
};

Default:

watchFiles: {
  paths: ['./src'],
  includes: [/\.(html|ejs|eta)$/],
  excludes: [
    /[\\/](node_modules|dist|test)$/, // ignore standard project dirs
    /[\\/]\..+$/, // ignore hidden dirs and files, e.g.: .git, .idea, .gitignore, etc.
    /package(?:-lock)*\.json$/, // ignore npm files
    /webpack\.(.+)\.js$/, // ignore Webpack config files
    /\.(je?pg|png|ico|webp|svg|woff2?|ttf|otf|eot)$/, // exclude binary assets
  ],
}

Allows to configure paths and files to watch file changes for rebuild in watch or serv mode.

ℹ️ Note

To watch changes with a live reload in the browser, you must additionally configure the watchFiles in devServer, see setup live reload.

Properties:

This options does not override the default values, but extends them.

For example, all source files are in the ./src directory, while some partials included in a template are in ./vendor/ directory, then add it to the paths:

watchFiles: {
  paths: ['vendor'],
},

If you want watch changes in some special files used in your template that are only loaded through the template engine, add them to the includes property:

watchFiles: {
  paths: ['vendor'],
  includes: [
    /data\.(js|json)$/,
  ],
},

To exclude watching of files defined in paths and includes, you can use the excludes option. This option has the priority over paths and files.

ℹ️ Note

To display all watched files, enable the verbose option.

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<a id="option-hot-update" name="option-hot-update"></a>

hotUpdate

Type: boolean Default: false

If the value is true, then in the serve or watch mode, the hot-update.js file is injected into each generated HTML file to enable the live reloading. Use this options only if you don't have a referenced source file of a script in html.

ℹ️ Note

The devServer.hot must be true.

If you already have a js file in html, this setting should be false as Webpack automatically injects the hot update code into the compiled js file.

Also see Setup Live Reload.

<a id="option-verbose" name="option-verbose"></a>

verbose

Type: 'auto'|boolean Default: false

The verbose option allows displaying in the console the processing information about extracted resources. All resources are grouped by their issuers.

Possible values:

ℹ️ Note

If you want to colorize the console output in your app, use the best Node.js lib ansis.

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<a id="option-loader-options" name="option-loader-options"></a>

loaderOptions

This is the reference to the loader options. You can specify loader options here in the plugin options to avoid explicitly defining the HtmlBundlerPlugin.loader in module.rules. The HtmlBundlerPlugin.loader will be added automatically.

For example, both configurations are functionally identical:

1) the variant using the loaderOptions, recommended for common use cases:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');
module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        index: 'src/views/index.ejs',
      },
      // compile a template into HTML using `ejs` module
      preprocessor: 'ejs',
      loaderOptions: {
        // resolve files specified in non-standard attributes 'data-src', 'data-srcset'
        sources: [{ tag: 'img', attributes: ['data-src', 'data-srcset'] }],
      },
    }),
  ],
};

2) the low level variant using the module.rules:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');
module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        index: 'src/views/index.ejs',
      },
    }),
  ],
  module: {
    rules: [
      {
        test: /.(html|ejs)$/,
        loader: HtmlBundlerPlugin.loader,
        options: {
          sources: [{ tag: 'img', attributes: ['data-src', 'data-srcset'] }],
          preprocessor: 'ejs',
        },
      },
    ],
  },
};

⚠️ Warning

If you don't know what it's for, don't define a module rule for template files. The plugin automatically configures this rule.

Define this rule only for special cases, e.g. when you have templates with different templating engines.
An example see by How to use some different template engines.

ℹ️ Note

Options defined in module.rules take precedence over the same options defined in loaderOptions.

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<a id="loader-options" name="loader-options"></a>

Loader options

<a id="default-loader" name="default-loader"></a> The default loader:

{
  test: /\.(html)$/,
  loader: HtmlBundlerPlugin.loader,
}

You can omit the loader in Webpack modules.rules. If the HtmlBundlerPlugin.loader is not configured, the plugin add it with default options automatically.

The default loader handles HTML files and EJS-like templates.

ℹ️ Note

It is recommended to define all loader options in the loaderOptions by the plugin options to keep the webpack config clean and smaller.

⚠️ Warning

The plugin works only with the own loader HtmlBundlerPlugin.loader. Do not use another loader. This loader replaces the functionality of html-loader and many other template loaders.

<a id="loader-option-sources" name="loader-option-sources"></a>

sources

Type:

type Sources =
  | boolean
  | Array<{
      tag?: string;
      attributes?: Array<string>;
      filter?: (props: {
        tag: string;
        attribute: string;
        value: string;
        parsedValue: Array<string>;
        attributes: { [attributeName: string]: string };
        resourcePath: string;
      }) => boolean | undefined;
    }>;

Default: true

The sources option allow to specify a tag attribute that should be resolved.

<a id="loader-option-sources-default" name="loader-option-sources-default"></a>

Default attributes

By default, resolves source files in the following tags and attributes:

TagAttributes
linkhref for type="text/css" rel="stylesheet" as="style" as="script"<br>imagesrcset for as="image"
scriptsrc
imgsrc srcset
imagehref xlink:href
usehref xlink:href
inputsrc (for type="image")
sourcesrc srcset
audiosrc
tracksrc
videosrc poster
objectdata

⚠️ Warning

It is not recommended to use the deprecated xlink:href attribute by the image and use tags.

ℹ️ Note

Automatically are processed only attributes containing a relative path or Webpack alias:

Url values are not processed:

Others not filename values are ignored, e.g.:

<a id="loader-option-sources-filter" name="loader-option-sources-filter"></a>

filter function

Using the filter function, you can enable/disable resolving of specific assets by tags and attributes.

The filter is called for all attributes of the tag defined as defaults and in sources option. The argument is an object containing the properties:

The processing of an attribute can be ignored by returning false.

To disable the processing of all attributes, set the sources option as false.

Examples of using argument properties:

{
  tag: 'img',
  // use the destructuring of variables from the object argument
  filter: ({ tag, attribute, value, attributes, resourcePath }) => {
    if (attribute === 'src') return false;
    if (value.endsWith('.webp')) return false;
    if ('srcset' in attributes && attributes['srcset'] === '') return false;
    if (resourcePath.indexOf('example')) return false;
    // otherwise return 'true' or nothing (undefined) to allow the processing
  },
}

The default sources can be extended with new tags and attributes.

For example, enable the processing for the non-standard data-src and data-srcset attributes in the img tag:

new HtmlBundlerPlugin({
  entry: {
    index: 'src/views/index.html',
  },
  loaderOptions: {
    sources: [
      {
        tag: 'img',
        attributes: ['data-src', 'data-srcset'],
      },
    ],
  },
});

You can use the filter function to allow the processing only specific attributes.

The filter function must return true or undefined to enable the processing of specified tag attributes. Return false to disable the processing.

For example, allow processing only for images in content attribute of the meta tag:

<html>
  <head>
    <!-- ignore the 'content' attribute via filter -->
    <meta name="theme-color" content="#ffffff" />
    <meta property="og:title" content="Frutis" />
    <meta property="og:image:type" content="image/png" />
    <meta property="og:video:type" content="video/mp4" />

    <!-- resolve the 'content' attribute via filter  -->
    <meta property="og:image" content="./frutis.png" />
    <meta property="og:video" content="./video.mp4" />
  </head>
  <body>
    <!-- resolve standard 'src' attribute -->
    <img src="./image.png" />
  </body>
</html>

Use the filter function:

new HtmlBundlerPlugin({
  entry: {
    index: 'src/views/index.html',
  },
  loaderOptions: {
    sources: [
      {
        tag: 'meta',
        attributes: ['content'],
        // allow to handle an image in the 'content' attribute of the 'meta' tag
        // when the 'property' attribute contains one of: 'og:image', 'og:video'
        filter: ({ attributes }) => {
          const attrName = 'property';
          const attrValues = ['og:image', 'og:video']; // allowed values of the property
          if (!attributes[attrName] || attrValues.indexOf(attributes[attrName]) < 0) {
            return false; // return false to disable processing
          }
          // return true or undefined to enable processing
        },
      },
    ],
  },
});

The filter can disable an attribute of a tag.

For example, disable the processing of default attribute srcset of the img tag:

new HtmlBundlerPlugin({
  entry: {
    index: 'src/views/index.html',
  },
  loaderOptions: {
    sources: [
      {
        tag: 'img',
        filter: ({ attribute }) => attribute !== 'srcset',
      },
    ],
  },
});

See also an example of using the filter function: How to resolve source image in <a href="image.jpg">.

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<a id="loader-option-root" name="loader-option-root"></a>

root

Type: string|boolean Default: false

The root option allow to resolve an asset file with leading / root path.

Defaults is disabled because the file with leading / is a valid URL in the public path, e.g. dist/. The files with leading / are not processed.

Define the root option as the absolute path to the source directory to enable the processing.

For example, there are project files:

./src/views/index.html
./src/styles/style.scss
./src/scripts/main.js
./src/images/apple.png

Define the root loader option:

new HtmlBundlerPlugin({
  entry: {
    index: 'src/views/index.html',
  },
  loaderOptions: {
    root: path.join(__dirname, 'src'),
  },
});

Now you can use the / root path for the source assets:

<html>
  <head>
    <link href="/styles/style.scss" rel="stylesheet" />
    <script src="/scripts/main.js" defer="defer"></script>
  </head>
  <body>
    <h1>Hello World!</h1>
    <img src="/images/apple.png" />
  </body>
</html>

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<a id="loader-option-context" name="loader-option-context"></a>

context

Type: string Default: undefined

The context option allow to resolve an asset file without leading / path.

For example, there are project files:

project/src/views/index.html
project/src/styles/style.scss
project/src/images/logo.png
otherDir/stock-photos/cologne.png // <= file outer your project directory

You can use the root option to use assets in your project directory and define the context option to use assets outer your project directory:

new HtmlBundlerPlugin({
  entry: {
    index: 'src/views/index.html',
  },
  loaderOptions: {
    root: path.resolve(__dirname, 'src'),
    context: path.resolve(__dirname, '../otherDir'),
  },
});

Now you can use the leading / for the assets in your project and w/o / for assets from outer directory:

<html>
  <head>
    <link href="/styles/style.scss" rel="stylesheet" />
  </head>
  <body>
    <h1>Hello World!</h1>
    <img src="/images/logo.png" />
    <img src="stock-photos/cologne.png" />
  </body>
</html>

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<a id="loader-option-before-preprocessor" name="loader-option-before-preprocessor"></a>

beforePreprocessor

See the description in the beforePreprocessor.

Usage in loaderOptions:

new HtmlBundlerPlugin({
  entry: {
    index: 'src/views/pages/',
  },
  loaderOptions: {
    beforePreprocessor: (content, { resourcePath, data }) => {
      // modify content
      return content;
    },
  },
});

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<a id="loader-option-preprocessor" name="loader-option-preprocessor"></a>

preprocessor

Type:

type Preprocessor =
  | false
  | 'eta'
  | 'ejs'
  | 'handlebars'
  | 'nunjucks'
  | 'pug'
  | 'twig'
  | ((
      content: string,
      loaderContext: LoaderContext<Object> & { data: { [key: string]: any } | string }
    ) => string | Promise<any> | undefined);

Default: 'eta'

You can use the preprocessor as a string for supported template engines, or define your own preprocessor as a function to use any template engine.

Supported templating engines "out of the box"

type Preprocessor = 'eta' | 'ejs' | 'handlebars' | 'nunjucks' | 'pug' | 'twig';

The preprocessor is ready to use the most popular templating engines: Eta, EJS, Handlebars, Nunjucks, Pug, Twig.

Defaults used the Eta templating engine, because Eta has the EJS-like syntax, is only 2KB gzipped and is much fasted than EJS. The npm package eta is already installed with this plugin.

You can pass a custom options of the templating engine using the preprocessorOptions.

For example, if you have EJS templates:

install npm package ejs

npm i -D ejs

define the preprocessor as the 'ejs' string

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');
module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        index: 'src/views/pages/home/index.ejs',
      },
      loaderOptions: {
        preprocessor: 'ejs',
      },
    }),
  ],
};

ℹ️ Note

Since the v2.2.0 is available new syntax, the preprocessor and the preprocessorOptions should be defined directly in the plugin option to simplify the config:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');
module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        index: 'src/views/pages/home/index.ejs',
      },
      preprocessor: 'ejs',
      preprocessorOptions: {...}
    }),
  ],
};

<a id="loader-option-preprocessor-custom" name="loader-option-preprocessor-custom"></a>

Custom templating engine

To use any templating engine, you can define the preprocessor as a function.

type Preprocessor = (
  content: string,
  loaderContext: LoaderContext<Object> & { data: { [key: string]: any } | string }
) => string | Promise<any> | undefined;

The function arguments:

The preprocessor is called for each entry file, before processing of the content. The function can be used to compile the template with any template engine, such as Eta, EJS, Handlebars, Mustache, Nunjucks, LiquidJS, etc.

Returns new content as a string for sync or Promise for async processing. When the function returns undefined, the contents of the template will not change.

The example for your own sync render function:

{
  preprocessor: (content, { data }) => render(content, data);
}

The example of using Promise for your own async render function:

{
  preprocessor: (content, { data }) =>
    new Promise((resolve) => {
      const result = render(content, data);
      resolve(result);
    });
}

The default preprocessor is pre-configured as the following function:

const { Eta } = require('eta');
const eta = new Eta({
  async: false, // defaults is false, wenn is true then must be used `await includeAsync()`
  useWith: true, // allow to use variables in template without `it.` scope
  views: process.cwd(), // directory that contains templates
});
preprocessor = (content, { data }) => eta.renderString(content, data);

ℹ️ Note

The plugin supports EJS-like templates "out of the box" therefore the HtmlBundlerPlugin.loader can be omitted in the Webpack config.

<a id="loader-option-preprocessor-disable" name="loader-option-preprocessor-disable"></a>

Disable templating engine

You can use this plugin to resolve all source asset files in any HTML-like template used by server-side rendering. In this case, disable the preprocessor. The plugin resolves all source files and replaces them with the output filenames. The original template remains unchanged except for the filenames being replaced.

{
  preprocessor: false,
}

See How to process a PHP template.

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<a id="loader-option-preprocessorOptions" name="loader-option-preprocessorOptions"></a>

preprocessorOptions

Type: Object Default: {}

With the preprocessorOptions you can pass template engine options when used the preprocessor as the string: eta, ejs, handlebars, nunjucks, twig. Each preprocessor has its own options, depend on using template engine.

This loader option is referenced as the preprocessorOptions plugin option to simplify the config.

<a id="loader-option-preprocessor-options-eta" name="loader-option-preprocessor-options-eta"></a>

Options for preprocessor: 'eta' (default)

{
  preprocessor: 'eta',
  preprocessorOptions: {
    async: false, // defaults 'false', wenn is 'true' then must be used `await includeAsync()`
    useWith: true, // defaults 'true', use variables in template without `it.` scope
    views: 'src/views', // relative path to directory that contains templates
    // views: path.join(__dirname, 'src/views'), // absolute path to directory that contains templates
  },
},

For the complete list of options see here.

For example, there are a template page and partials:

src/views/page/home.html
src/views/includes/gallery.html
src/views/includes/teaser.html
src/views/partials/footer.html
src/views/partials/menu/nav.html
src/views/partials/menu/top/desktop.html

Include the partials in the src/views/page/home.html template with the include():

<%~ include('teaser.html') %>
<%~ include('menu/nav.html') %>
<%~ include('menu/top/desktop.html') %>
<%~ include('footer.html') %>

If partials have .eta extensions, then the extension can be omitted in the include argument.

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<a id="loader-option-preprocessor-options-ejs" name="loader-option-preprocessor-options-ejs"></a>

Options for preprocessor: 'ejs'

{
  preprocessor: 'ejs',
  preprocessorOptions: {
    async: false, // defaults 'false'
    // defaults process.cwd(), root path for includes with an absolute path (e.g., /file.html)
    root: path.join(__dirname, 'src/views/'), // defaults process.cwd()
    // defaults [], an array of paths to use when resolving includes with relative paths
    views: [
      'src/views/includes', // relative path
      path.join(__dirname, 'src/views/partials'), // absolute path
    ],
  },
},

For the complete list of options see here.

For example, there are template page and partials:

src/views/page/home.html
src/views/includes/gallery.html
src/views/includes/teaser.html
src/views/partials/footer.html
src/views/partials/menu/nav.html
src/views/partials/menu/top/desktop.html

Include the partials in the src/views/page/home.html template with the include():

<!-- root path -->
<%- include('/includes/gallery.html') %>

<!-- views paths -->
<%- include('menu/top/desktop.html') %>
<%- include('menu/nav.html') %>
<%- include('teaser.html') %>
<%- include('footer.html') %>

If you have partials with .ejs extensions, then the extension can be omitted.

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<a id="loader-option-preprocessor-options-handlebars" name="loader-option-preprocessor-options-handlebars"></a>

Options for preprocessor: 'handlebars'

The preprocessor has built-in include helper, to load a partial file directly in a template without registration of partials.

The include helper has the following de facto standard options:

{
  preprocessor: 'handlebars',
  preprocessorOptions: {
    // defaults process.cwd(), root path for includes with an absolute path (e.g., /file.html)
    root: path.join(__dirname, 'src/views/'), // defaults process.cwd()
    // defaults [], an array of paths to use when resolving includes with relative paths
    views: [
      'src/views/includes', // relative path
      path.join(__dirname, 'src/views/partials'), // absolute path
    ],
  },
},

For example, there are template page and partials:

src/views/page/home.html
src/views/includes/gallery.html
src/views/includes/teaser.html
src/views/partials/footer.html
src/views/partials/menu/nav.html
src/views/partials/menu/top/desktop.html

Include the partials in the src/views/page/home.html template with the include helper:

<!-- root path -->
{{ include '/includes/gallery' }}

<!-- views paths -->
{{ include 'menu/top/desktop' }}
{{ include 'menu/nav' }}
{{ include 'teaser' }}
{{ include 'footer' }}

The include helper automatically resolves .html and .hbs extensions, it can be omitted.

The runtime option

The path to the handlebars runtime library. The path can be absolute or relative to node_modules directory. Defaults runtime file is handlebars/runtime. This options is used only by import templates in JavaScript, in compile mode.

The partials option

Type: Array<string>|Object Default: []

If you use the partials syntax {{> footer }} to include a file, then use the partials option. Partials will be auto-detected in paths recursively and registered under their relative paths, without an extension.

{
  preprocessor: 'handlebars',
  preprocessorOptions: {
    // an array of relative or absolute paths to partials
    partials: [
      'src/views/includes', // relative path
      path.join(__dirname, 'src/views/partials'), // absolute path
    ],
  },
},

For example, if the partial path is the src/views/partials then the file src/views/partials/menu/top/desktop.html will have the partial name menu/top/desktop.

You can define all partials manually using the option as an object:

{
  preprocessor: 'handlebars',
    preprocessorOptions: {
    // define partials manually
    partials: {
      teaser: path.join(__dirname, 'src/views/includes/teaser.html'),
      gallery: path.join(__dirname, 'src/views/includes/gallery.html'),
      footer: path.join(__dirname, 'src/views/partials/footer.html'),
      'menu/nav': path.join(__dirname, 'src/views/partials/menu/nav.html'),
      'menu/top/desktop': path.join(__dirname, 'src/views/partials/menu/top/desktop.html'),
    },
  },
},

Include the partials in the src/views/page/home.html template:

{{> menu/top/desktop }}
{{> menu/nav }}
{{> teaser }}
{{> gallery }}
{{> footer }}

The helpers option

Type: Array<string>|Object Default: []

When the helpers is an array of relative or absolute paths to helpers, then the name of a helper is the relative path to the helper file without an extension.

For example, there are helper files:

src/views/helpers/bold.js
src/views/helpers2/italic.js
src/views/helpers2/wrapper/span.js

The preprocessor options:

{
  preprocessor: 'handlebars',
  preprocessorOptions: {
    // an array of relative or absolute paths to helpers
    helpers: [
      'src/views/helpers',
      'src/views/helpers2',
    ],
  },
},

Usage of helpers:

{{#bold}}The bold text.{{/bold}} {{#italic}}The italic text.{{/italic}}

<!-- the helper with namespace `wrapper/span` -->
{{#[wrapper/span]}}The text wrapped with span tag.{{/[wrapper/span]}}

ℹ️ Note

You can define helpers manually using name: function object:

{
  preprocessor: 'handlebars',
  preprocessorOptions: {
    // define helpers manually
    helpers: {
      bold: (options) => new Handlebars.SafeString(`<strong>${options.fn(this)}</strong>`),
    },
  },
},

This plugin has own build-in helpers:

For the complete list of Handlebars compile options see here.

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<a id="loader-option-preprocessor-options-tempura" name="loader-option-preprocessor-options-tempura"></a>

Options for preprocessor: 'tempura'

Tempura is a light and fast template engine with Handlebars-like syntax.

The preprocessor has built-in include helper, to load a partial file.

{
  preprocessor: 'tempura',
  preprocessorOptions: {
    // defaults process.cwd(), root path for includes with an absolute path (e.g., /file.html)
    root: path.join(__dirname, 'src/views/'), // defaults process.cwd()
    // defaults [], an array of paths to use when resolving includes with relative paths
    views: [
      'src/views/includes', // relative path
      path.join(__dirname, 'src/views/partials'), // absolute path
    ],
    blocks: {
      // define here custom helpers
      bar: ({ value }) => `<bar>${value}</bar>`,
    },
  },
},

For all available options, see the Tempura API options.

Using build-in include helper.

The src attribute contains a path to the partial file.

The path relative to current working directory (defaults webpack config directory):

{{#include src='src/views/partials/header.hbs' }}

The path relative to directory defined in root option, e.g. root: 'src/view':

{{#include src='partials/header.hbs' }}

The path relative to one of directories defined in views option, e.g. views: ['src/views/partials']:

{{#include src='header.hbs' }}

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<a id="loader-option-preprocessor-options-nunjucks" name="loader-option-preprocessor-options-nunjucks"></a>

Options for preprocessor: 'nunjucks'

{
  preprocessor: 'nunjucks',
  preprocessorOptions: {
    // here are preprocessor options
    // an array of relative or absolute templates paths, defaults the current working directory
    views: [
      'src/views/includes',
      'src/views/partials',
    ],
    async: false, // defaults 'false'
    jinjaCompatibility: false, // installs support for Jinja compatibility, defaults 'false'

    // here are original Nunjucks options
    autoescape: true, // escape dangerous characters, defaults 'true'
    // ...
  },
},

For all available options, see the Nunjucks API configure.

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<a id="loader-option-preprocessor-options-pug" name="loader-option-preprocessor-options-pug"></a>

Options for preprocessor: 'pug'

ℹ️ Note

The pug preprocessor based on the @webdiscus/pug-loader source code and has the same options and features.

{
  preprocessor: 'pug',
  preprocessorOptions: {
    // in 99.9% of common use cases you don't need any pug options

    // available useful embedded filters
    embedFilters: {
      // enable the `:escape` filter
      escape: true,
      
      // enable the `:code` filter
      code: {
        className: 'language-', // class name of `<code>` tag
      },
      
      // enable `:highlight` filter
      highlight: {
        use: 'prismjs', // use the `prismjs` module as highlighter, must be installed
        verbose: true,
      },
      
      // enable `:markdown` filter for markdown only, w/o code blocks
      markdown: true,
      // - OR - you can enable highlighter for code blocks used in markdown
      markdown: {
        highlight: {
          use: 'prismjs', // use the `prismjs` module as highlighter, must be installed
          verbose: true,
        },
      },
    }
  },
},

See the documentation and examples for the embedded filters.
See the pug compiler options.

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<a id="loader-option-preprocessor-options-twig" name="loader-option-preprocessor-options-twig"></a>

Options for preprocessor: 'twig'

The TwigJS have few useful options:

{
  preprocessor: 'twig',
  preprocessorOptions: {
    async: false,
    autoescape: false,
    namespaces: {
      layouts: 'src/views/layouts',
      partials: 'src/views/partials',
    },
  },
},

The used namespace must begin with the leading @ symbol:

{% extends "@layouts/default.twig" %}
{% include "@partials/articles/sidebar.twig" %}

You can use a relative path:

{% extends "../layouts/default.twig" %}
{% include "../partials/articles/sidebar.twig" %}

⚠️ Warning

The dynamic including is not supported.
For example, passing myTemplate as a parameter does not work:

{# page.twig #}
{% extends myTemplate %}

⚠️ Warning

The Twig template containing tabs will not be compiled into HTML.
Use the spaces as an indent in templates. The tabs are not supported by TwigJS.

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<a id="loader-option-data" name="loader-option-data"></a>

data

Type: Object|string Default: {}

Since v2.5.0 the data option is referenced in the plugin options.

The properties of the data option are available as global variables in all templates. To pass variables to a specific template, use the entry.{name}.data option.

Data as an object

Type: Object

The data defined as an object are loaded once with Webpack start.

Data as file path

Type: string

The string value is an absolute or relative filename of a JSON or JS file. The JS file must export an object. The data file will be reloaded after changes.

ℹ️ Note

Use the data as a path to dynamically update variables in a template without restarting Webpack.

⚠️ Warning

The entry.{name}.data property overrides the same property defined in the loader data.

For example, there are variables defined in both the entry property and the plugin option:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');

module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        index: {
          import: 'src/views/home.html',
          data: {
            // page specifically variables
            title: 'Home', // overrides the `title` defined in the loader data
            headline: 'Homepage',
          },
          // - OR -
          data: 'src/data/home.json',
        },
        about: 'src/views/about.html',
      },
      data: {
        // global variables for all pages
        title: 'Default Title',
        globalData: 'Global Data',
      },
      // - OR -
      data: 'src/data/global.js',
    }),
  ],
};

JSON data file src/data/home.json

{
  "title": "Home",
  "headline": "Homepage"
}

JS data file src/data/global.js

module.exports = {
  title: 'Default Title',
  globalData: 'Global Data',
};

In the ./src/views/home.html template are available following variables:

{
  title: 'Home',
  headline: 'Homepage',
  globalData: 'Global Data',
}

In the ./src/views/about.html template are available following variables:

{
  title: 'Default Title',
  globalData: 'Global Data',
}

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<a id="template-engine" name="template-engine"></a>

Template engines

Using the preprocessor, you can compile any template with a template engine such as:

<!-- > ℹ️ **Note** > > For Pug templates use the [pug-plugin](https://github.com/webdiscus/pug-plugin). > This plugin works on the same codebase but has additional Pug-specific options and features. -->

<a id="using-template-eta" name="using-template-eta"></a>

Using the Eta

Supported "out of the box"

Eta is compatible* with EJS syntax, is smaller and faster than EJS.

For example, there is the template src/views/page/index.eta

<html>
  <body>
    <h1><%= headline %></h1>
    <ul class="people">
      <% for (let i = 0; i < people.length; i++) {%>
      <li><%= people[i] %></li>
      <% } %>
    </ul>
    <%~ include('/src/views/partials/footer') %>
  </body>
</html>

The minimal Webpack config:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');

module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        index: {
          // output dist/index.html
          import: './src/views/page/index.eta',
          data: {
            headline: 'Breaking Bad',
            people: ['Walter White', 'Jesse Pinkman'],
          },
        },
      },
    }),
  ],
};

The default preprocessor is eta, you can omit it:

new HtmlBundlerPlugin({
  entry: {
    index: './src/views/page/index.eta',
  },
  // preprocessor: 'eta', // defaults is used Eta
  // preprocessorOptions: {...},
});

See the eta preprocessor options.

<a id="eta-compatibilty-with-ejs" name="eta-compatibilty-with-ejs"></a>

⚠️ Warning

For compatibility the Eta compiler with the EJS templates, the default preprocessor use the useWith: true Eta option to use variables in template without the Eta-specific it. scope.

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<a id="using-template-ejs" name="using-template-ejs"></a>

Using the EJS

You need to install the ejs package:

npm i -D ejs

For example, there is the template src/views/page/index.ejs

<html>
  <body>
    <h1><%= headline %></h1>
    <ul class="people">
      <% for (let i = 0; i < people.length; i++) {%>
      <li><%= people[i] %></li>
      <% } %>
    </ul>
    <%- include('/src/views/partials/footer.html'); %>
  </body>
</html>

Define the preprocessor as ejs:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');

module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        index: {
          // output dist/index.html
          import: './src/views/page/index.ejs',
          data: {
            headline: 'Breaking Bad',
            people: ['Walter White', 'Jesse Pinkman'],
          },
        },
      },
      preprocessor: 'ejs', // use EJS templating engine
      // preprocessorOptions: {...},
    }),
  ],
};

See the ejs preprocessor options.

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<a id="using-template-handlebars" name="using-template-handlebars"></a>

Using the Handlebars

You need to install the handlebars package:

npm i -D handlebars

For example, there is the template src/views/page/home.hbs

<!DOCTYPE html>
<html>
<head>
  <title>{{ title }}</title>
</head>
<body>
  {{> header }}
  <div class="container">
    <h1>Handlebars</h1>
    <div>{{ arraySize persons }} persons:</div>
    <ul class="person">
      {{#each persons}}
        {{> person person=.}}
      {{/each}}
    </ul>
  </div>
  {{> footer }}
</body>
</html>

Where the {{> header }}, {{> person person=.}} and {{> footer }} are partials.

Define the preprocessor as handlebars:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');

module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        // define templates here
        index: {
          import: 'src/views/pages/home.hbs', // => dist/index.html
          // pass data to template as an object
          // data: { title: 'Handlebars', persons: [...] },
          // OR define the data file
          data: 'src/views/pages/homeData.js',
        },
      },
      // use handlebars templating engine
      preprocessor: 'handlebars',
      // define handlebars options
      preprocessorOptions: {
        partials: ['src/views/partials'],
        helpers: {
          arraySize: (array) => array.length,
        },
      },
    }),
  ],
};

See the handlebars preprocessor options.

Source code of the example

Open in StackBlitz

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<a id="using-template-tempura" name="using-template-tempura"></a>

Using the Tempura

You need to install the tempura package:

npm i -D tempura

For example, there is the template src/views/page/home.hbs

<!DOCTYPE html>
<html>
<head>
  <title>{{ title }}</title>
</head>
<body>
  {{#include src='header.hbs' }}
  <div class="container">
    <h1>Tempura</h1>
    <div>{{ persons.length }} persons:</div>
    <ul class="person">
      {{#each persons as person}}
        <li>{{person.name}} is {{person.age}} years old.</li>
      {{/each}}
    </ul>
  </div>
  {{#include src='footer.hbs' }}
</body>
</html>

Define the preprocessor as tempura:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');

module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        // define templates here
        index: {
          import: 'src/views/pages/home.hbs', // => dist/index.html
          // pass data to template as an object
          data: { 
            title: 'Tempura',
             persons: [
                { name: 'Robert', age: 30 },
                ...
             ], 
          },
        },
      },
      // use tempura templating engine
      preprocessor: 'tempura',
      // define options
      preprocessorOptions: {
        views: ['src/views/partials'],
      },
    }),
  ],
};

See the tempura preprocessor options.

Source code of the example

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<a id="using-template-mustache" name="using-template-mustache"></a>

Using the Mustache

You need to install the mustache package:

npm i -D mustache

For example, there is the template src/views/page/index.mustache

<html>
  <body>
    <h1>{{ headline }}</h1>
    <ul class="people">
      {{#people}}
      <li>{{.}}</li>
      {{/people}}
    </ul>
  </body>
</html>

Add the template compiler to preprocessor:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');
const Mustache = require('mustache');

module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      test: /\.(html|mustache)$/, // add the test option to match *.mustache files in entry
      index: {
        import: './src/views/page/index.mustache',
        data: {
          headline: 'Breaking Bad',
          people: ['Walter White', 'Jesse Pinkman'],
        },
      },
      // define preprocessor as the function that shoud return a string or promise
      preprocessor: (content, { data }) => Mustache.render(content, data),
    }),
  ],
};

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<a id="using-template-nunjucks" name="using-template-nunjucks"></a>

Using the Nunjucks

You need to install the nunjucks package:

npm i -D nunjucks

For example, there is the template src/views/page/index.njk

<html>
  <body>
    <h1>{{ headline }}!</h1>
    <ul class="people">
      {% for name in people %}
      <li class="name">{{ name }}</li>
      {% endfor %}
    </ul>
  </body>
</html>

Define the preprocessor as nunjucks:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');

module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        index: {
          import: './src/views/page/index.njk',
          data: {
            headline: 'Breaking Bad',
            people: ['Walter White', 'Jesse Pinkman'],
          },
        },
      },
      preprocessor: 'nunjucks', // use Nunjucks templating engine
      // preprocessorOptions: {...},
    }),
  ],
};

See the nunjucks preprocessor options.

↑ back to contents

<a id="using-template-pug" name="using-template-pug"></a>

Using the Pug

You need to install the pug package:

npm i -D pug

For example, there is the layout template src/views/layout/default.pug

html
  head
    title= title
    script(src="@scripts/main.js" defer="defer")
  body
    h1= headline
    block content
    include @partials/footer

The page template src/views/pages/home.pug can be extended from the layout:

extends @layouts/default

block content
  ul#people
    each item in people
      li= item

Define the preprocessor as pug:

const path = require('path');
const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');

module.exports = {
  resolve: {
    alias: {
      '@scripts': path.join(__dirname, 'src/scripts/'), // alias to scripts used in template
      '@layouts': path.join(__dirname, 'src/views/layouts/'), // alias to template layouts
      '@partials': path.join(__dirname, 'src/views/partials/'), // alias to template partials
    },
  },
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        index: {
          import: 'src/views/page/home.pug',
          data: {
            title: 'Strartpage',
            headline: 'Breaking Bad',
            people: ['Walter White', 'Jesse Pinkman'],
          },
        },
      },
      preprocessor: 'pug', // use Pug templating engine
      preprocessorOptions: {
        // Pug options
      },
    }),
  ],
};

See the pug options.

↑ back to contents

<a id="using-template-twig" name="using-template-twig"></a>

Using the TwigJS

You need to install the twig package:

npm i -D twig

For example, there is the layout template src/views/layout/default.twig

<!DOCTYPE html>
<html>
  <head>
    <title>{{ title }}</title>
    <script src="@scripts/main.js" defer="defer"></script>
  </head>
  <body>
    <h1>{{ headline }}!</h1>
    <div id="content">{% block content %}{% content %}</div>
    {% include "@partials/footer.twig" %}
  </body>
</html>

The page template src/views/pages/home.twig can be extended from the layout:

{% extends '@layouts/default.twig' %}

{% block content %}
  <ul id="people">
    {% for item in people %}
        <li>{{ item }}</li>
    {% endfor %}
  </ul>
{% endblock %}

Define the preprocessor as twig:

const path = require('path');
const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');

module.exports = {
  resolve: {
    alias: {
      '@scripts': path.join(__dirname, 'src/scripts/'), // alias to scripts used in template
    },
  },
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        index: {
          import: 'src/views/page/home.twig',
          data: {
            title: 'Strartpage',
            headline: 'Breaking Bad',
            people: ['Walter White', 'Jesse Pinkman'],
          },
        },
      },
      preprocessor: 'twig', // use TwigJS templating engine
      preprocessorOptions: {
        // aliases used for extends/include
        namespaces: {
          layouts: 'src/views/layout/',
          partials: 'src/views/partials/',
        },
      },
    }),
  ],
};

See the twig preprocessor options.

↑ back to contents

<a id="using-template-liquidjs" name="using-template-liquidjs"></a>

Using the LiquidJS

You need to install the liquidjs package:

npm i -D liquidjs

For example, there is the template src/views/page/index.liquid

<html>
  <body>
    <h1>{{ headline }}!</h1>
    <ul class="people">
      {% for name in people %}
      <li class="name">{{ name }}</li>
      {% endfor %}
    </ul>
  </body>
</html>

Add the template compiler to preprocessor:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');
const { Liquid } = require('liquidjs');

const LiquidEngine = new Liquid();

module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      test: /\.(html|liquid)$/, // add the test option to match *.liquid files in entry
      entry: {
        index: {
          import: './src/views/page/index.liquid',
          data: {
            headline: 'Breaking Bad',
            people: ['Walter White', 'Jesse Pinkman'],
          },
        },
      },
      // async parseAndRender method return the promise
      preprocessor: (content, { data }) => LiquidEngine.parseAndRender(content, data),
    }),
  ],
};

↑ back to contents

<a id="template-in-js" name="template-in-js"></a>

Using template in JavaScript

The preprocessor works in two modes: render and compile.

Render mode

The render is the default mode for the template defined in the entry option. The rendered template is an HTML string, which is saved as an HTML file.

You can import the template file as a generated HTML string in JS using the ?render query. To pass simple variables into the imported template you can use query parameters, e.g.: ?render&name=Arnold&age=25. To pass complex variables such as an array or an object use the global data option.

ℹ️ Note

At runtime in JavaScript will be used the already rendered HTML from the template.

For example:

import html from './partials/star-button.html?render&buttonText=Star';

document.getElementById('star-button').innerHTML = html;

./partials/star-button.html

<button class="btn-star">
  <!-- you can use a source image file with webpack alias,
       in the bundle it will be auto replaced with the output asset filename -->
  <img src="@images/star.svg">
  <!-- the `buttonText` variable is passed via query -->
  <span><%= buttonText %></span>
</button>

<a id="compile-mode" name="compile-mode"></a>

Compile mode

The compile is the default mode for the template imported in JavaScript file. The compiled template is a template function, which can be executed with passed variables in the runtime on the client-side in the browser.

For example:

import tmpl from './partials/people.ejs';

// template variables
const locals = {
  people: [
    'Walter White',
    'Jesse Pinkman',
  ],
};

// render template function with variables in browser
document.getElementById('people').innerHTML = tmpl(locals);

./partials/people.ejs

<!-- you can use a source image file with webpack alias,
     in the bundle it will be auto replaced with the output asset filename -->
<img src="@images/people.png">
<ul class="people">
  <% for (let i = 0; i < people.length; i++) {%>
  <li><%= people[i] %></li>
  <% } %>
</ul>

⚠️ Warning

Not all template engines can generate a template function that can be executed with local variables at runtime.

Template engines that do support the template function on client-side

Template engines that do NOT support the template function on client-side

↑ back to contents

<a id="setup-live-reload" name="setup-live-reload"></a>

Setup Live Reload

To enable reloading of the browser after changes, add the devServer option to the Webpack config:

module.exports = {
  // enable live reload
  devServer: {
    static: path.join(__dirname, 'dist'),
    watchFiles: {
      paths: ['src/**/*.*'],
      options: {
        usePolling: true,
      },
    },
  },
};

⚠️ Warning

If you don't have a referenced source script file in HTML, then set the hotUpdate option to true to enable live reload. Besides, the devServer.hot must be true (defaults).

↑ back to contents

<a id="recipe-keep-folder-structure-html" name="recipe-keep-folder-structure-html"></a>

How to keep source directory structure for HTML

Define the entry option as a path to templates. The output path will have the same directory structure. For details, see the entry path.

↑ back to contents

<a id="recipe-keep-folder-structure-assets" name="recipe-keep-folder-structure-assets"></a>

How to keep source directory structure for assets

Define the filename as a function.

For example, we want to keep original directory structure for fonts, which can be in the source or in the node_modules directory:

node_modules/material-icons/iconfont/material-icons-sharp.woff2
node_modules/material-symbols/material-symbols-sharp.woff2
src/assets/fonts/Roboto/Roboto-Regular.woff2

Use the following function:

{
  test: /[\\/]fonts|node_modules[\\/].+(woff(2)?|ttf|otf|eot|svg)$/i,
    type: 'asset/resource',
    generator: {
    // keep original directory structure
    filename: ({ filename }) => {
      const srcPath = 'src/assets/fonts';
      const regExp = new RegExp(`[\\\\/]?(?:${path.normalize(srcPath)}|node_modules)[\\\\/](.+?)$`);
      const assetPath = path.dirname(regExp.exec(filename)[1].replace('@', '').replace(/\\/g, '/'));

      return `fonts/${assetPath}/[name][ext][query]`;
    },
  },
},

The destructed filename argument of the function is a source file. It can be absolute or relative.

The output directory dist/ will have the same structure:

dist/fonts/material-icons/iconfont/material-icons-sharp.woff2
dist/fonts/material-symbols/material-symbols-sharp.woff2
dist/fonts/Roboto/Roboto-Regular.woff2

The example to keep original directory structure for images:

{
  test: /[\\/]images|node_modules[\\/].+(png|jpe?g|webp|ico|svg)$/i,
    type: 'asset/resource',
    generator: {
    // keep original directory structure
    filename: ({ filename }) => {
      const srcPath = 'src/assets/images';
      const regExp = new RegExp(`[\\\\/]?(?:${path.normalize(srcPath)}|node_modules)[\\\\/](.+?)$`);
      const assetPath = path.dirname(regExp.exec(filename)[1].replace('@', '').replace(/\\/g, '/'));

      return `images/${assetPath}/[name].[hash:8][ext]`;
    },
  },
},

ℹ️ Note

For images, it is recommended to use the hashed output filename.

↑ back to contents

<a id="recipe-use-images-in-html" name="recipe-use-images-in-html"></a>

How to use source image files in HTML

Add to Webpack config the rule:

module: {
  rules: [
    {
      test: /\.(png|jpe?g|ico|svg)$/,
      type: 'asset/resource',
      generator: {
        filename: 'assets/img/[name].[hash:8][ext]',
      },
    },
  ],
}

Add a source file using a relative path or Webpack alias in HTML:

<html>
  <head>
    <link href="./favicon.ico" rel="icon" />
  </head>
  <body>
    <img src="./apple.png" srcset="./apple1.png 320w, ./apple2.png 640w" alt="apple" />
    <picture>
      <source srcset="./fig1.jpg, ./fig2.jpg 320w, ./fig3.jpg 640w" />
    </picture>
  </body>
</html>

The generated HTML contains hashed output images filenames:

<html>
  <head>
    <link href="/assets/img/favicon.05e4dd86.ico" rel="icon" />
  </head>
  <body>
    <img
      src="/assets/img/apple.f4b855d8.png"
      srcset="/assets/img/apple1.855f4bd8.png 320w, /assets/img/apple2.d8f4b855.png 640w"
      alt="apple" />
    <picture>
      <source
        srcset="
          /assets/img/fig1.605e4dd8.jpg,
          /assets/img/fig2.8605e4dd.jpg 320w,
          /assets/img/fig3.e4605dd8.jpg 640w
        " />
    </picture>
  </body>
</html>

↑ back to contents

<a id="recipe-responsive-images" name="recipe-responsive-images"></a>

How to resize and generate responsive images

To resize or generate responsive images is recommended to use the responsive-loader.

Install additional packages:

npm i -D responsive-loader sharp

To resize an image use the query parameter size:

<!-- resize source image to max. 640px -->
<img src="./image.png?size=640" />

To generate responsible images use in srcset attribute the query parameter sizes als JSON5 to avoid parsing error, because many images must be separated by commas , but we use the comma to separate sizes for one image:

<!-- responsible images with different sizes: 320px, 480px, 640px -->
<img src="./image.png?size=480" srcset="./image.png?{sizes:[320,480,640]}" />

You can convert source image to other output format. For example, we have original image 2000px width as PNG and want to resize to 640px and save as WEBP:

<img src="./image.png?size=640&format=webp" />

You can create a small inline image placeholder. To do this, use the following query parameters:

<img
  src="./image.png?placeholder=true&placeholderSize=35&prop=placeholder"
  srcset="./image.png?{sizes:[320,480,640]}" />

The generated HTML:

<img
  src="data:image/png;base64,iVBORw0K ..."
  srcset="/img/image-320w.png 320w, /img/image-480w.png 480w, /img/image-640w.png 640w" />

Add to Webpack config the rule for responsive images:

module.exports = {
  module: {
    rules: [
      {
        test: /\.(png|jpe?g|webp)$/,
        type: 'asset/resource',
        use: {
          loader: 'responsive-loader',
          options: {
            // output filename of images, e.g. dist/assets/img/image-640w.png
            name: 'assets/img/[name]-[width]w.[ext]',
            sizes: [640], // max. image size, if 'size' query is not used
          },
        },
      },
      // ... other loaders
    ],
  },
};

↑ back to contents

<a id="recipe-preload-fonts" name="recipe-preload-fonts"></a>

How to preload fonts

To preload resources such as fonts, use the preload plugin option.

For example, there is the style used a font that should be preloaded:

styles.scss

@font-face {
  font-family: 'MyFont';
  // load source fonts using the `@fonts` Webpack alias to the font directory
  src:
    local(MyFont Regular),
    url('@fonts/myfont.woff2') format('woff2'),
    url('@fonts/myfont.woff') format('woff');
}

body {
  font-family: 'MyFont', serif;
}

The template index.html where is loaded the source style:

<html>
  <head>
    <title>Demo</title>
    <!-- include source style -->
    <link href="./style.scss" rel="stylesheet" />
  </head>
  <body>
    <h1>Hello World!</h1>
  </body>
</html>

Use the minimal Webpack config:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');

module.exports = {
  resolve: {
    alias: {
      '@fonts': path.join(__dirname, 'src/assets/fonts/'), // => add alias to the font directory
    },
  },
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        index: 'src/views/index.html', // => template where is loaded the style with fonts
      },
      css: {
        filename: 'css/[name].[contenthash:8].css', // => filename of extracted CSS
      },
      // => add the preload option with the config for fonts
      preload: [
        {
          test: /\.(woff2|woff)$/,
          attributes: { as: 'font', crossorigin: true },
        },
      ],
    }),
  ],
  module: {
    rules: [
      // => add the style rule
      {
        test: /\.(css|sass|scss)$/,
        use: ['css-loader', 'sass-loader'],
      },
      // => add the font rule
      {
        test: /\.(woff2|woff)$/,
        type: 'asset/resource',
        generator: {
          filename: 'fonts/[name][ext]',
        },
      },
    ],
  },
};

ℹ️ Note

Font preloading requires the crossorigin attribute to be set. See font preload.

The generated HTML contains the preload tag with the font:

<html>
  <head>
    <title>Demo</title>
    <!-- preload fonts detected in style -->
    <link rel="preload" href="fonts/myfont.woff2" as="font" type="font/woff2" crossorigin="true" />
    <link rel="preload" href="fonts/myfont.woff" as="font" type="font/woff" crossorigin="true" />
    <!-- compiled style -->
    <link href="css/style.1f4faaff.css" rel="stylesheet" />
  </head>
  <body>
    <h1>Hello World!</h1>
  </body>
</html>

ℹ️ Note

You don't need a plugin to copy files from source directory to public. All source fonts will be coped to output directory automatically.

↑ back to contents

<a id="recipe-inline-css" name="recipe-inline-css"></a>

How to inline CSS in HTML

There are two ways to inline CSS in HTML:

The inline option can take the following values: false, true and 'auto'. For details see the inline option.

ℹ️ Note

The individual ?inline query parameter takes precedence over the globally css.inline option.
For example, if css.inline = true and in HTML a single file has the ?inline=false query, this file will be extracted in an output file, while all other styles will be inlined.

For example, there are two SCSS files:

main.scss

$bgColor: steelblue;
body {
  background-color: $bgColor;
}

styles.scss:

$color: red;
h1 {
  color: $color;
}

There is the ./src/views/index.html with both style files:

<html>
  <head>
    <link href="./main.scss" rel="stylesheet" />
    <link href="./style.scss" rel="stylesheet" />
  </head>
  <body>
    <h1>Hello World!</h1>
  </body>
</html>

To inline all CSS globally add the css.inline option:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');
module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        index: 'src/views/index.html',
      },
      css: {
        // adds CSS to the DOM by injecting a `<style>` tag
        inline: true,
        // output filename of extracted CSS, used if inline is false
        filename: 'css/[name].[contenthash:8].css',
      },
    }),
  ],
  module: {
    rules: [
      {
        test: /\.(css|sass|scss)$/,
        use: ['css-loader', 'sass-loader'],
      },
    ],
  },
};

The generated HTML contains inlined CSS:

<html>
  <head>
    <style>
      body {
        background-color: steelblue;
      }
    </style>
    <style>
      h1 {
        color: red;
      }
    </style>
  </head>
  <body>
    <h1>Hello World!</h1>
  </body>
</html>

To inline a single CSS, add the ?inline query to a style file which you want to inline:

<html>
  <head>
    <!-- file CSS -->
    <link href="./main.scss" rel="stylesheet" />
    <!-- inline CSS -->
    <link href="./style.scss?inline" rel="stylesheet" />
  </head>
  <body>
    <h1>Hello World!</h1>
  </body>
</html>

The generated HTML contains inline CSS already processed via Webpack:

<html>
  <head>
    <!-- file CSS -->
    <link href="/css/main.05e4dd86.css" rel="stylesheet" />
    <!-- inline CSS -->
    <style>
      h1 {
        color: red;
      }
    </style>
  </head>
  <body>
    <h1>Hello World!</h1>
  </body>
</html>

ℹ️ Note

To enable the source map in inline CSS set the Webpack option devtool.

↑ back to contents

<a id="recipe-inline-js" name="recipe-inline-js"></a>

How to inline JS in HTML

There are two ways to inline CSS in HTML:

The inline option can take the following values: false, true and 'auto'. For details see the inline option.

ℹ️ Note

The individual ?inline query parameter takes precedence over the globally js.inline option.
For example, if js.inline = true and in HTML a single file has the ?inline=false query, this file will be extracted in an output file, while all other scripts will be inlined.

For example, there are two JS files:

main.js

console.log('>> main.js');

script.js

console.log('>> script.js');

There is the ./src/views/index.html with both script files:

<html>
  <head>
    <script src="./main.js" defer="defer"></script>
  </head>
  <body>
    <h1>Hello World!</h1>
    <script src="./script.js"></script>
  </body>
</html>

To inline all JS globally add the js.inline option:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');
module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        index: 'src/views/index.html',
      },
      js: {
        // adds JavaScript to the DOM by injecting a `<script>` tag
        inline: true,
        // output filename of compiled JavaScript, used if inline is false
        filename: 'js/[name].[contenthash:8].js',
      },
    }),
  ],
};

The generated HTML contains inlined JS scripts:

<html>
  <head>
    <script>
      (() => {
        'use strict';
        console.log('>> main.js');
      })();
    </script>
  </head>
  <body>
    <h1>Hello World!</h1>
    <script>
      (() => {
        'use strict';
        console.log('>> script.js');
      })();
    </script>
  </body>
</html>

To inline a single JS file, add the ?inline query to a script file which you want to inline:

<html>
  <head>
    <!-- file JS -->
    <script src="./main.js" defer="defer"></script>
    <!-- inline JS -->
    <script src="./script.js?inline"></script>
  </head>
  <body>
    <h1>Hello World!</h1>
  </body>
</html>

The generated HTML contains inline JS already compiled via Webpack:

<html>
  <head>
    <!-- file JS -->
    <script src="js/main.992ba657.js" defer="defer"></script>
    <!-- inline JS -->
    <script>
      (() => {
        'use strict';
        console.log('>> script.js');
      })();
    </script>
  </head>
  <body>
    <h1>Hello World!</h1>
  </body>
</html>

ℹ️ Note

If Webpack is started as serve or watch, the inlined JS code will contain additional HMR code. Don't worry it is ok, so works Webpack live reload.

To enable the source map in inline JS set the Webpack option devtool.

↑ back to contents

<a id="recipe-inline-image" name="recipe-inline-image"></a>

How to inline SVG, PNG images in HTML

You can inline the images in two ways:

Add to Webpack config the rule:

module: {
  rules: [
    {
      test: /\.(png|jpe?g|svg|webp|ico)$/i,
      oneOf: [
        // inline image using `?inline` query
        {
          resourceQuery: /inline/,
          type: 'asset/inline',
        },
        // auto inline by image size
        {
          type: 'asset',
          parser: {
            dataUrlCondition: {
              maxSize: 1024,
            },
          },
          generator: {
            filename: 'assets/img/[name].[hash:8][ext]',
          },
        },
      ],
    },
  ],
}

The plugin automatically inlines images smaller then maxSize.

↑ back to contents

<a id="recipe-inline-all-assets-to-html" name="recipe-inline-all-assets-to-html"></a>

How to inline all resources into single HTML file

The bundler plugin can generate a single HTML file included all embedded dependencies such as JS, CSS, fonts, images (PNG, SVG, etc..).

The fonts and images used in CSS will be inlined into CSS. The generated CSS including inlined images will be inlined into HTML.

Just use the following config:

const path = require('path');
const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');

module.exports = {
  mode: 'production',
  output: {
    path: path.join(__dirname, 'dist/'),
  },
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        index: './src/views/index.html',
      },
      css: {
        inline: true, // inline CSS into HTML
      },
      js: {
        inline: true, // inline JS into HTML
      },
    }),
  ],
  module: {
    rules: [
      {
        test: /\.(css|sass|scss)$/,
        use: ['css-loader', 'sass-loader'],
      },
      // inline all assets: images, svg, fonts
      {
        test: /\.(png|jpe?g|webp|svg|woff2?)$/i,
        type: 'asset/inline',
      },
    ],
  },
  performance: false, // disable warning max size
};

Open in StackBlitz

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<a id="recipe-resolve-attr-json" name="recipe-resolve-attr-json"></a>

How to resolve source assets in an attribute containing JSON value

For example, source images should be defined in the custom data-image attribute of the a tag:

<a data-image='{ "imgSrc": "./pic1.png", "bgImgSrc": "./pic2.png" }' href="#" >
  ...
</a>

To resolve such files, just use the require() function:

<a data-image='{ "imgSrc": require("./pic1.png"), "bgImgSrc": require("./pic2.png") }' href="#" >
  ...
</a>

Add to sources loader option the data-image attribute for the a tag:

new HtmlBundlerPlugin({
  entry: {
    index: './src/index.html',
  },
  loaderOptions: {
    sources: [
      {
        tag: 'a',                   // <= specify the 'a' tag
        attributes: ['data-image'], // <= specify custom attribute for the 'a' tag
      },
    ],
  },
}),

The custom attribute will contains in the generated HTML the resolved output assets filenames:

<a data-image='{ "imgSrc": "img/pic1.da3e3cc9.png", "bgImgSrc": "img/pic2.e3cc9da3.png" }' href="#" >
  ...
</a>

↑ back to contents

<a id="recipe-resolve-attr-style-url" name="recipe-resolve-attr-style-url"></a>

How to resolve source image in the style attribute

For example, there is the source image file defined in the style attribute as the background of the div tag:

<div style="background-image: url(./pic1.png);"></div>

The source image file can be a file relative to the template or you can use a webpack alias to the image directory.

ℹ️ Note

This is BAD practice. Use it only in special cases. The background image should be defined in CSS.

By default, the style attribute is not parsed and therefore needs to be configured:

new HtmlBundlerPlugin({
  entry: {
    index: './src/index.html',
  },
  loaderOptions: {
    sources: [
      {
        tag: 'div',            // <= specify the tag where should be parsed style
        attributes: ['style'], // <= specify the style attribute
      },
    ],
  },
}),

The plugin resolves the url() value and replaces it in the generated HTML with the output filename:

<div style="background-image: url(assets/img/pic1.d4711676.png);"></div>

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<a id="recipe-resolve-attr-href-a-image" name="recipe-resolve-attr-href-a-image"></a>

How to resolve source image in <a href="image.jpg">

For example, you want to link a small image as a preview to open the full-size image in a new tab or pop-up window.

A typical example:

<!-- href contains HTML file -->
<a href="index.html">home</a> | <a href="about.html">about</a>

<!-- href contains image file, which should be resolved -->
<a href="./images/cat-fullsize.jpg" target="_blank">
   <img src="./images/cat-preview.jpg" />
</a>

To resolve images in the href attribute of a tag, just enable it using the loaderOptions.sources option.

loaderOptions: {
  sources: [
    {
      tag: 'a',
      attributes: ['href'],
    },
  ],
},

Problem by resolving

All href attributes of all <a> tags will now be resolved, which could cause an error if the href contained an HTML file, e.g. <a href="index.html">.

Solution

Use the filter function to avoid resolving non-image files.

loaderOptions: {
  sources: [
    {
      tag: 'a',
      attributes: ['href'],
      filter: ({ value }) => !value.endsWith('.html'), // return false to ignore *.html files
    },
  ],
},

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<a id="recipe-dynamic-load-css" name="recipe-dynamic-load-css"></a>

How to load CSS file dynamically

For dynamic file loading, we need the output filename of extracted CSS from a source style file. To get the CSS output filename in JavaScript, you can use the url query:

import cssUrl from './style.scss?url';
// - OR -
const cssUrl = require('./style.scss?url');

Where the ./style.scss is the source SCSS file relative to the JavaScript file.

To load a CSS file dynamically, you can use following function:

import cssUrl from './style.scss?url';

function loadCSS(url) {
  const style = document.createElement('link');
  style.href = url;
  style.rel = 'stylesheet';
  document.head.appendChild(style);
}

loadCSS(cssUrl);

The CSS will be extracted into separate file and the cssUrl variable will contains the CSS output filename.

Since 2023, many browsers support the modern way to add the stylesheets into DOM without creating the link tag.

import cssUrl from './style.scss?url';

async function loadCSS(url) {
  const response = await fetch(url);
  const css = await response.text();
  const sheet = new CSSStyleSheet();
  sheet.replaceSync(css);
  document.adoptedStyleSheets = [sheet];
}

loadCSS(cssUrl);

See the browser compatibility.

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<a id="recipe-css-modules" name="recipe-css-modules"></a>

How to import CSS class names in JS

Required: css-loader >= 7.0.0

To import style class names in JS, add in the webpack config the modules option into css-loader:

{
  test: /\.(css)$/,
  use: [
    {
      loader: 'css-loader',
      options: {
        modules: {
          localIdentName: '[name]__[local]--[hash:base64:5]',
          exportLocalsConvention: 'camelCase',
        },
      },
    },
  ],
},

For example there is ./style.css file:

.error-message {
  color: red;
}

In ./main.js file you can use the class name with camelCase:

import styles from './style.css';

element.innerHTML = `<div class="${styles.errorMessage}">`;

The imported styles object contains generated class names like followings:

{
  errorMessage: 'main__error-message--gvFM4',
}

Read more information about CSS Modules.

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<a id="recipe-css-style-sheet" name="recipe-css-style-sheet"></a>

How to import CSS stylesheet in JS

Using the css-loader option exportType as css-style-sheet you can import the CSS stylesheets as the instance of the CSSStyleSheet object.

Import a CSS module script and apply it to a document or a shadow root like this:

import sheet from './style.scss?sheet';

document.adoptedStyleSheets = [sheet];
shadowRoot.adoptedStyleSheets = [sheet];

You can use the ?sheet URL query to import a style file as stylesheets. The query must be configured in the webpack config:

module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        index: './src/index.html',
      },
      js: {
        filename: '[name].[contenthash:8].js',
      },
      css: {
        filename: '[name].[contenthash:8].css',
      },
    }),
  ],
  module: {
    rules: [
      {
        test: /\.(s?css)$/,
        oneOf: [
          // Import CSS/SCSS source file as a CSSStyleSheet object
          {
            resourceQuery: /sheet/, // <= the query, e.g. style.scss?sheet
            use: [
              {
                loader: 'css-loader',
                options: {
                  exportType: 'css-style-sheet', // <= define this option
                },
              },
              {
                loader: 'sass-loader',
              },
            ],
          },
          // Import CSS/SCSS source file as a CSS string
          {
            use: [
              'css-loader',
              'sass-loader',
            ],
          }
        ],
      }
    ],
  },
};

Using the universal configuration above you can apply CSS stylesheets in JS and extract CSS into separate file or inject CSS into HTML:

import sheet from './style.scss?sheet'; // import as CSSStyleSheet object
import './style2.scss?inline'; // the extracted CSS will be injected into HTML
import './style3.scss'; // the extracted CSS will be saved into separate output file

// apply stylesheet to document and shadow root
document.adoptedStyleSheets = [sheet];
shadowRoot.adoptedStyleSheets = [sheet];

This is useful for custom elements and shadow DOM.

More information:

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<a id="recipe-load-js-css-from-node-modules" name="recipe-load-js-css-from-node-modules"></a>

How to load JS and CSS from node_modules in template

Some node modules specifies compiled bundle files for the browser in package.json.

For example:

You can use only the module name, the plugin automatically resolves browser ready files for script and style:

<html>
<head>
  <!-- plugin resolves the bootstrap/dist/css/bootstrap.css -->
  <link href="bootstrap" rel="stylesheet">
  <!-- plugin resolves the bootstrap/dist/js/bootstrap.js -->
  <script src="bootstrap" defer="defer"></script>
</head>
<body>
  <h1>Hello World!</h1>
</body>
</html>

If you need to load a specific version of a file, use the module name and the path to that file:

<html>
<head>
  <link href="bootstrap/dist/css/bootstrap.rtl.css" rel="stylesheet">
  <script src="bootstrap/dist/js/bootstrap.bundle.js" defer="defer"></script>
</head>
<body>
  <h1>Hello World!</h1>
</body>
</html>

⚠️ Warning

Don't use a relative path to node_modules, like ../node_modules/bootstrap. The plugin resolves node module path by the name automatically.

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<a id="recipe-import-style-from-node-modules" name="recipe-import-style-from-node-modules"></a>

How to import CSS or SCSS from node_modules in SCSS

The plugin resolves default style files defined in node_modules automatically.

For example, import source styles of material-icons:

// import source styles from `material-icons` module
@use 'material-icons';

// define short class name for original `.material-icons-outlined` class name from module
.mat-icon {
  @extend .material-icons-outlined;
}

You can import a file from a module using the module name and the path to the file:

@use 'MODULE_NAME/path/to/style';

⚠️ Warning

The file extension, e.g. .scss, .css, must be omitted.

⚠️ Warning

Use the @use instead of @import, because it is deprecated.

For example, import the style theme tomorrow from the prismjs module:

@use 'prismjs/themes/prism-tomorrow.min';

⚠️ Warning

Don't use resolve-url-loader!

The HTML bundler plugin resolves styles faster than resolve-url-loader and don't requires using the source map in sass-loader options.

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<a id="recipe-preprocessor-php" name="recipe-preprocessor-php"></a>

How to process a PHP template (.phtml)

The plugin can replace the source filenames of scripts, styles, images, etc. with their output filenames in a template.

For example, there is the PHP template src/views/index.phtml:

<?php
  $title = 'Home';
?>
<html>
<head>
  <title><?= $title ?></title>
  <link href="./style.css" rel="stylesheet">
  <script src="./main.js" defer="defer"></script>
</head>
<body>
  <h1>Hello World!</h1>
</body>
</html>

The PHP template should not be compiled into pure HTML, but only should be processed the source assets. In this case, the preprocessor must be disabled.

module.exports = {
  output: {
    path: path.join(__dirname, 'dist/'), // output directory
  },
  plugins: [
    new HtmlBundlerPlugin({
      test: /\.(php|phtml)$/i, // define template extensions to be processed
      filename: '[name].phtml', // define output filename for templates defined in entry
      entry: {
        index: './src/views/index.phtml',
      },
      js: {
        filename: 'js/[name].[contenthash:8].js',
      },
      css: {
        filename: 'css/[name].[contenthash:8].css',
      },
      preprocessor: false, // disable preprocessor
    }),
  ],
};

The processed PHP template dist/index.phtml:

<?php
  $title = 'Home';
?>
<html>
<head>
  <title><?= $title ?></title>
  <link href="css/style.026fd625.css" rel="stylesheet">
  <script src="js/main.3347618e.js" defer="defer"></script>
</head>
<body>
  <h1>Hello World!</h1>
</body>
</html>

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<a id="recipe-pass-data-to-templates" name="recipe-pass-data-to-templates"></a>

How to pass data into multiple templates

You can pass variables into template using a template engine, e.g. Handlebars. For multiple page configuration, better to use the Nunjucks template engine maintained by Mozilla.

For example, you have several pages with variables.
Both pages have the same layout src/views/layouts/default.html

<!doctype html>
<html>
  <head>
    <title>{{ title }}</title>
    <!-- block for specific page styles -->
    {% block styles %}{% endblock %}
    <!-- block for specific page scripts -->
    {% block scripts %}{% endblock %}
  </head>
  <body>
    <main class="main-content">
      <!-- block for specific page content -->
      {% block content %}{% endblock %}
    </main>
  </body>
</html>

src/views/pages/home/index.html

{% extends "src/views/layouts/default.html" %} {% block styles %}
<!-- include source style -->
<link href="./home.scss" rel="stylesheet" />
{% endblock %} {% block scripts %}
<!-- include source script -->
<script src="./home.js" defer="defer"></script>
{% endblock %} {% block content %}
<h1>{{ filmTitle }}</h1>
<p>Location: {{ location }}</p>
<!-- @images is the Webpack alias for the source images directory -->
<img src="@images/{{ imageFile }}" />
{% endblock %}

src/views/pages/about/index.html

{% extends "src/views/layouts/default.html" %} {% block styles %}
<link href="./about.scss" rel="stylesheet" />
{% endblock %} {% block scripts %}
<script src="./about.js" defer="defer"></script>
{% endblock %} {% block content %}
<h1>Main characters</h1>
<ul>
  {% for item in actors %}
  <li class="name">{{ item.firstname }} {{ item.lastname }}</li>
  {% endfor %}
</ul>
{% endblock %}

Webpack config

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');
const Nunjucks = require('nunjucks');

// Note:
// If your pages have a lot of variables, it's a good idea to define them separately
// to keep the configuration clean and clear.
const entryData = {
  // variables for home page
  home: {
    title: 'Home',
    filmTitle: 'Breaking Bad',
    location: 'Albuquerque, New Mexico',
    imageFile: 'picture.png',
  },
  // variables for about page
  about: {
    title: 'About',
    actors: [
      {
        firstname: 'Walter',
        lastname: 'White, "Heisenberg"',
      },
      {
        firstname: 'Jesse',
        lastname: 'Pinkman',
      },
    ],
  },
};

module.exports = {
  resolve: {
    alias: {
      '@images': path.join(__dirname, 'src/assets/images'),
    },
  },
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        // define your templates here
        index: {
          // => dist/index.html
          import: 'src/views/pages/home/index.html',
          data: entryData.home,
        },
        about: {
          // => dist/about.html
          import: 'src/views/pages/about/index.html',
          data: entryData.about,
        },
      },
      js: {
        filename: 'js/[name].[contenthash:8].js',
      },
      css: {
        filename: 'css/[name].[contenthash:8].css',
      },
      // the Nunjucks template engine is supported "out of the box"
      preprocessor: 'nunjucks',
      // -OR- use as the function for full controll
      // preprocessor: (content, { data }) => Nunjucks.renderString(content, data),
    }),
  ],
  module: {
    rules: [
      // styles
      {
        test: /\.(css|sass|scss)$/,
        use: ['css-loader', 'sass-loader'],
      },
      // images
      {
        test: /\.(png|svg|jpe?g|webp)$/i,
        type: 'asset/resource',
        generator: {
          filename: 'assets/img/[name].[hash:8][ext]',
        },
      },
    ],
  },
};

The generated dist/index.html

<!doctype html>
<html>
  <head>
    <title>Home</title>
    <link href="css/home.2180238c.css" rel="stylesheet" />
    <script src="js/home.790d746b.js" defer="defer"></script>
  </head>
  <body>
    <main class="main-content">
      <h1>Breaking Bad</h1>
      <p>Breaking Bad is an American crime drama</p>
      <p>Location: Albuquerque, New Mexico</p>
      <img src="assets/img/picture.697ef306.png" alt="location" />
    </main>
  </body>
</html>

The generated dist/about.html

<!doctype html>
<html>
  <head>
    <title>About</title>
    <link href="css/about.2777c101.css" rel="stylesheet" />
    <script src="js/about.1.c5e03c0e.js" defer="defer"></script>
  </head>
  <body>
    <main class="main-content">
      <h1>Main characters</h1>
      <ul>
        <li class="name">Walter White, &quot;Heisenberg&quot;</li>
        <li class="name">Jesse Pinkman</li>
      </ul>
    </main>
  </body>
</html>

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<a id="recipe-diff-templates" name="recipe-diff-templates"></a>

How to use some different template engines

When you have many templates with different syntax, you can use a separate module rules for each template engine. For example, in your project are mixed templates with EJS and Handlebars syntax.

- src/views/ejs/home.ejs
- src/views/hbs/about.hbs

To handle different templates, define the test plugin option that must match those templates and add a preprocessor for each template type in the module rules.

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');
const ejs = require('ejs');
const Handlebars = require('handlebars');

module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      test: /\.(ejs|hbs)$/, // <= specify extensions for all template types here
      entry: {
        index: 'src/views/ejs/home.ejs', // EJS template
        about: 'src/views/hbs/about.hbs', // Handlebars template
      },
    }),
  ],
  module: {
    rules: [
      // the rule for EJS
      {
        test: /\.ejs$/,
        loader: HtmlBundlerPlugin.loader, // universal template loader
        options: {
          preprocessor: 'ejs',
          preprocessorOptions: {
            views: [path.join(__dirname, 'src/views/ejs/partials')],
          },
        },
      },
      // the rule for Handlebars
      {
        test: /\.hbs$/,
        loader: HtmlBundlerPlugin.loader, // universal template loader
        options: {
          preprocessor: 'handlebars',
          preprocessorOptions: {
            views: [path.join(__dirname, 'src/views/hbs/partials')],
          },
        },
      },
    ],
  },
};

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<a id="recipe-split-chunks" name="recipe-split-chunks"></a>

How to configure splitChunks

Webpack tries to split every entry file, include template files, which completely breaks the compilation process in the plugin.

To avoid this issue, you must specify which scripts should be split, using optimization.splitChunks.cacheGroups:

module.exports = {
  optimization: {
    splitChunks: {
-     chunks: 'all', // <= DO NOT use this here
      cacheGroups: {
        scripts: {
          test: /\.(js|ts)$/, // <= IMPORTANT: split only script files
+         chunks: 'all', // <= DEFINE it here only
        },
      },
    },
  },
};

ℹ️ Note

In the test option must be specified all extensions of scripts which should be split.

⚠️ Warning

DO NOT use the chunks: 'all' option globally!

The splitChunks.chunks: 'all' option splits all types of chunks, but it make no sense, because we need split only scripts. Templates, CSS, images and other assets can't be split.

Define chunks: 'all' only in a cache group where is specified the test option for your scripts.

‼️ The splitChunks.chunks option will be automatically removed, because some assets can't be resolved or output files may be corrupted!

See details by splitChunks.cacheGroups.

For example, in a template are used the scripts and styles from node_modules:

<html>
  <head>
    <title>Home</title>
    <link href="bootstrap/dist/css/bootstrap.min.css" rel="stylesheet" />
    <script src="bootstrap/dist/js/bootstrap.min.js" defer="defer"></script>
  </head>
  <body>
    <h1>Hello World!</h1>
    <script src="./main.js"></script>
  </body>
</html>

ℹ️ Note

In the generated HTML, all script tags remain in their original places, and the split chunks will be added there in the order in which Webpack generated them.

In this use case the optimization.splitChunks.cacheGroups.{cacheGroup}.test option must match exactly only JS files from node_modules:

module.exports = {
  optimization: {
    runtimeChunk: 'single',
    splitChunks: {
      cacheGroups: {
        vendor: {
          test: /[\\/]node_modules[\\/].+\.(js|ts)$/, // <= IMPORTANT: split only script files
          chunks: 'all', // <= DEFINE it here only
        },
      },
    },
  },
};

⚠️ Warning

If you will to use the test as /[\\/]node_modules[\\/], without extension specification, then Webpack concatenates JS code together with CSS in one file and Webpack compilation will failed or generate files with a wrong content. Webpack can't differentiate CSS module from JS module, therefore you MUST match only JS files.

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<a id="recipe-split-chunks-keep-module-name" name="recipe-split-chunks-keep-module-name"></a>

How to keep package name for split chunks from node_modules

To save split chunks under a custom name use optimization.splitChunks.cacheGroups.{cacheGroup}.name as function.

For example, many node modules are imported in the main.js:

import { Button } from 'bootstrap';
import _, { map } from 'underscore';
// ...

There is a template used the main.js ./src/views/index.html:

<html>
  <head>
    <!-- include source script -->
    <script src="./main.js" defer="defer"></script>
  </head>
  <body>
    <h1>Hello World!</h1>
  </body>
</html>

Then, use the optimization.splitChunks.cacheGroups.{cacheGroup}.name as following function:

const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');

module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      entry: {
        index: 'src/views/index.html',
      },
      js: {
        filename: 'js/[name].[contenthash:8].js',
        chunkFilename: 'js/[id].[contenthash:8].js',
      },
    }),
  ],
  optimization: {
    runtimeChunk: true,
    splitChunks: {
      maxSize: 1000000, // split chunks bigger than 100KB, defaults is 20KB
      cacheGroups: {
        app: {
          test: /\.(js|ts)$/, // <= IMPORTANT: split only script files
          chunks: 'all', // <= define it only in a cache group
          name({ context }, chunks, groupName) {
            // save split chunks of the node module under package name
            if (/[\\/]node_modules[\\/]/.test(context)) {
              const moduleName = context.match(/[\\/]node_modules[\\/](.*?)(?:[\\/]|$)/)[1].replace('@', '');
              return `npm.${moduleName}`;
            }
            // save split chunks of the application
            return groupName;
          },
        },
      },
    },
  },
};

⚠️ Warning

The group name MUST be different from the script names used in the template. Otherwise, a chunk name conflict occurs.

For example, if you are already using main.js in the template, the group name should not be main. Take another name, e.g. app.

The split files will be saved like this:

dist/js/runtime.9cd0e0f9.js
dist/js/npm.popperjs/core.f96a1152.js <- split chunks of node modules
dist/js/npm.bootstrap.f69a4e44.js
dist/js/npm.underscore.4e44f69a.js
dist/js/main.3010da09.js <- base code of main script
dist/js/app-5fa74877.7044e96a.js <- split chinks of main script
dist/js/app-d6ae2b10.92215a4e.js
dist/js/app-5fa74877.1aceb2db.js

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<a id="recipe-split-css" name="recipe-split-css"></a>

How to split CSS files

⚠️ Warning

Splitting CSS to many chunks is principally impossible. Splitting works only for JS files.

Using the bundler plugin, all your style source files should be specified directly in the template. You can import style files in JavaScript, like it works using the mini-css-extract-plugin and html-webpack-plugin, but it is a bad practice and processing is slower.

You can separate the styles into multiple bundles yourself.

For example, there are style files used in your app:

- components/banner/style.scss 150 KB
- components/button/style.scss  50 KB
- components/menu/style.scss    50 KB
- components/modal/style.scss  100 KB
- components/panel/style.scss  100 KB
- styles/main.scss  250 KB

We want to have a bundle file ~250 KB, then create the bundles manually:

styles/bundle01.scss 200 KB

@use '../components/banner/style.scss';
@use '../components/button/style.scss';

styles/bundle02.scss 250 KB

@use '../components/menu/style.scss';
@use '../components/modal/style.scss';
@use '../components/panel/style.scss';

Add the bundles in the template:

<html>
  <head>
    <title>Home</title>
    <link href="./styles/bundle01.scss" rel="stylesheet" />
    <link href="./styles/bundle02.scss" rel="stylesheet" />
    <link href="./styles/main.scss" rel="stylesheet" />
  </head>
  <body>
    <h1>Hello World!</h1>
  </body>
</html>

If you use vendor styles in your style file, then vendor styles will not be saved to a separate file, because sass-loader generates one CSS bundle code.

styles.scss

@use 'bootstrap/scss/bootstrap';
body {
  color: bootstrap.$primary;
}
// ...

If you want save module styles separate from your styles, then load them in a template separately:

<html>
  <head>
    <title>Home</title>
    <!-- include module styles -->
    <link href="bootstrap/dist/css/bootstrap.min.css" rel="stylesheet" />
    <!-- include your styles -->
    <link href="./style.scss" rel="stylesheet" />
  </head>
  <body>
    <h1>Hello World!</h1>
    <script src="./main.js"></script>
  </body>
</html>

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<a id="solutions" name="solutions"></a>

Problems & Solutions

<a id="solutions-resolve-extensions" name="solutions-resolve-extensions"></a>

Automatic resolving of file extensions

Defaults, the Webpack resolves the omitted .js extension. If you use the TypeScript, you can add the .ts extension to be resolved.

For example, you have the files:

- moduleA.js
- moduleB.ts
- app.ts
- app.scss

The file extensions can be omitted:

app.ts

import moduleA from './moduleA';
import moduleB from './moduleB';

To allow this magic, you should configure the resolve.extensions Webpack option.

module.exports = {
  //...
  resolve: {
    extensions: ['.js', '.ts'],
  },
};

Problem with styles

If you import style files in your script and want automatically to resolve the .css, .scss extensions, e.g., as the following:

app.ts

import moduleA from './moduleA';
import moduleB from './moduleB';

// import app.scss file
import './app'; // <= DON'T DO IT!

module.exports = {
  //...
  resolve: {
    extensions: ['.js', '.ts', '.scss'], // <= DO NOT mix script and style extensions
  },
};

If you use as above, it won't work.

Solution

To import styles in a script, you MUST use a style extension and not add a style extension to the resolve.extensions option.

app.ts

import moduleA from './moduleA';
import moduleB from './moduleB';

import './app.scss'; // <= use the style extension

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<a id="solutions-import-url-in-css" name="solutions-import-url-in-css"></a>

How to use @import url() in CSS

⚠️ Warning

Don't use @import in CSS. It's very bad practice.

Bad example, main.css:

@import 'path/to/style.css';

The plugin does not support handling of @import url() in CSS. Imported url will be passed 1:1 into resulting CSS.

Problem: defaults, css-loader handles @import at-rule, which causes an issue in the plugin.

Solution: add the import: false into css-loader options:

{
  test: /\.(css)$/i,
  loader: 'css-loader',
  options: {
    import: false, // disable handling of @import at-rule in CSS
  },
},

⚠️ Warning

The *.css files imported in CSS are not handled, therefore these files must be manually copied to the dist/ folder using the copy-webpack-plugin.

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How to disable resolving in commented out tag

In default attributes, files will be resolved automatically, regardless of whether the tag is commented out or not. This is not a bug, it is a feature for very fast attribute parsing.

If you commented out a tag and don't want to resolve files in the tag's attributes, rename the attribute. For example: href -> x-href or src -> x-src.

<!-- <link x-href="./styles.scss" rel="stylesheet /> -->
<!-- <script x-src="./main.js" defer="defer"></script> -->
<!-- <img x-src="./image.png"> -->

If used any template engine (defaults is Eta) then can be used templating comments <%/* ... */%>.

<%/* <link rel="stylesheet href="./style.scss" /> Single line comment w/o resolving */%>

<%/*
  Multiline comment w/o resolving of files in attributes
  <img src="./image1.png" />
  <img src="./image2.png" />
*/%>

The generated HTML will not contain templating comments.

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Also See

License

ISC