Awesome
vfile-matter
vfile utility parse YAML front matter.
Contents
What is this?
This package parses YAML frontmatter, when found in a file, and exposes it as
file.data.matter
.
It can optionally strip the frontmatter, which is useful for languages that do
not understand frontmatter, but stripping can make it harder to deal with
languages that do understand it, such as markdown, because it messes up
positional info of warnings and errors.
When should I use this?
Frontmatter is a metadata format in front of content. It’s typically written in YAML and is often used with markdown. This mechanism works well when you want authors, that have some markup experience, to configure where or how the content is displayed or supply metadata about content.
When using vfiles with markdown, you are likely also using remark, in which
case you should use remark-frontmatter
, instead of
stripping frontmatter.
Install
This package is ESM only. In Node.js (version 16+), install with npm:
npm install vfile-matter
In Deno with esm.sh
:
import {matter} from 'https://esm.sh/vfile-matter@5'
In browsers with esm.sh
:
<script type="module">
import {matter} from 'https://esm.sh/vfile-matter@5?bundle'
</script>
Use
Say our document example.html
contains:
---
title: Hello, world!
---
<p>Some more text</p>
…and our module example.js
looks as follows:
import {read} from 'to-vfile'
import {matter} from 'vfile-matter'
const file = await read('example.html')
matter(file, {strip: true})
console.log(file.data)
console.log(String(file))
…now running node example.js
yields:
{matter: {title: 'Hello, world!'}}
<p>Some more text</p>
API
This package exports the identifier matter
.
There is no default export.
matter(file[, options])
Parse the YAML front matter in a file and expose it as file.data.matter
.
If no matter is found in the file, nothing happens, except that
file.data.matter
is set to an empty object ({}
).
If the file value is an Uint8Array
, assumes it is encoded in UTF-8.
Parameters
Returns
Nothing (undefined
).
Options
Configuration (TypeScript type).
Fields
strip
(boolean
, default:false
). — remove the YAML front matter from the fileyaml
(YamlOptions
, default:{}
) — configuration for the YAML parser, passed toyaml
asx
inyaml.parse('', x)
YamlOptions
Options for the YAML parser (TypeScript type).
Equivalent to the combination of
ParseOptions
,
DocumentOptions
,
SchemaOptions
, and
ToJsOptions
.
Type
type YamlOptions = ParseOptions &
DocumentOptions &
SchemaOptions &
ToJsOptions
Types
This package is fully typed with TypeScript.
It exports the additional types Options
and
YamlOptions
.
To type file.data.matter
, you can augment DataMap
from vfile
as follows:
declare module 'vfile' {
interface DataMap {
matter: {
// `file.data.matter.string` is typed as `string | undefined`.
title?: string | undefined
}
}
}
export {} // You may not need this, but it makes sure the file is a module.
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, vfile-matter@^5
,
compatible with Node.js 16.
Contribute
See contributing.md
in vfile/.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, organization, or community you agree to abide by its terms.