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hast-util-find-and-replace

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hast utility to find and replace things.

Contents

What is this?

This package is a utility that lets you find patterns (string, RegExp) in text and replace them with nodes (such as elements). It’s aware of HTML (such as ignoring <style> and <script> by default).

When should I use this?

This utility is typically useful when you have regexes and want to modify hast. One example is when you have some form of “mentions” (such as /@([a-z][_a-z0-9])\b/gi) and want to create links to persons from them.

Install

This package is ESM only. In Node.js (version 16+), install with npm:

npm install hast-util-find-and-replace

In Deno with esm.sh:

import {findAndReplace} from 'https://esm.sh/hast-util-find-and-replace@5'

In browsers with esm.sh:

<script type="module">
  import {findAndReplace} from 'https://esm.sh/hast-util-find-and-replace@5?bundle'
</script>

Use

import {h} from 'hastscript'
import {findAndReplace} from 'hast-util-find-and-replace'
import {inspect} from 'unist-util-inspect'

const tree = h('p', [
  'Some ',
  h('em', 'emphasis'),
  ', ',
  h('strong', 'importance'),
  ', and ',
  h('code', 'code'),
  '.'
])

findAndReplace(tree, [
  [/and/gi, 'or'],
  [/emphasis/gi, 'em'],
  [/importance/gi, 'strong'],
  [
    /code/gi,
    function ($0) {
      return h('a', {href: '//example.com#' + $0}, $0)
    }
  ]
])

console.log(inspect(tree))

Yields:

element<p>[9]
│ properties: {}
├─0 text "Some "
├─1 element<em>[1]
│   │ properties: {}
│   └─0 text "em"
├─2 text ", "
├─3 element<strong>[1]
│   │ properties: {}
│   └─0 text "strong"
├─4 text ", "
├─5 text "or"
├─6 text " "
├─7 element<code>[1]
│   │ properties: {}
│   └─0 element<a>[1]
│       │ properties: {"href":"//example.com#code"}
│       └─0 text "code"
└─8 text "."

API

This package exports the identifiers defaultIgnore and findAndReplace. There is no default export.

defaultIgnore

Default tag names to ignore (Array<string>).

The defaults are math, script, style, svg, and title.

findAndReplace(tree, list[, options])

Find patterns in a tree and replace them.

The algorithm searches the tree in preorder for complete values in Text nodes. Partial matches are not supported.

Parameters
Returns

Nothing (undefined).

Find

Pattern to find (TypeScript type).

Strings are escaped and then turned into global expressions.

Type
type Find = RegExp | string

FindAndReplaceList

Several find and replaces, in array form (TypeScript type).

Type
type FindAndReplaceList = Array<FindAndReplaceTuple>

See FindAndReplaceTuple.

FindAndReplaceTuple

Find and replace in tuple form (TypeScript type).

Type
type FindAndReplaceTuple = [Find, Replace?]

See Find and Replace.

Options

Configuration (TypeScript type).

Fields

RegExpMatchObject

Info on the match (TypeScript type).

Fields

Replace

Thing to replace with (TypeScript type).

Type
type Replace = ReplaceFunction | string | null | undefined

See ReplaceFunction.

ReplaceFunction

Callback called when a search matches (TypeScript type).

Parameters

The parameters are the result of corresponding search expression:

Returns

Thing to replace with:

Types

This package is fully typed with TypeScript. It exports the additional types Find, FindAndReplaceList, FindAndReplaceTuple, Options, RegExpMatchObject, Replace, and ReplaceFunction.

Compatibility

Projects maintained by the unified collective are compatible with maintained versions of Node.js.

When we cut a new major release, we drop support for unmaintained versions of Node. This means we try to keep the current release line, hast-util-find-and-replace@^5, compatible with Node.js 16.

Security

Use of hast-util-find-and-replace can open you up to a cross-site scripting (XSS) attack if a value used to replace is unsafe. Use hast-util-santize to make the hast tree safe.

The following example shows how a script is injected that runs when loaded in a browser.

const tree = h('p', 'This and that.')

findAndReplace(tree, 'and', function () {
  return h('script', 'alert(1)')
})

Yields:

<p>This <script>alert(1)</script> that.</p>

Related

Contribute

See contributing.md in syntax-tree/.github for ways to get started. See support.md for ways to get help.

This project has a code of conduct. By interacting with this repository, organisation, or community you agree to abide by its terms.

License

MIT © Titus Wormer

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