https://github.com/rehypejs/rehype-infer-description-meta
rehype plugin to infer file metadata from the contents of the document
https://github.com/rehypejs/rehype-infer-description-meta
description excerpt file hast meta rehype rehype-plugin summary truncate
Last synced: 3 months ago
JSON representation
rehype plugin to infer file metadata from the contents of the document
- Host: GitHub
- URL: https://github.com/rehypejs/rehype-infer-description-meta
- Owner: rehypejs
- License: mit
- Created: 2021-09-10T07:14:01.000Z (about 4 years ago)
- Default Branch: main
- Last Pushed: 2023-09-02T08:42:46.000Z (about 2 years ago)
- Last Synced: 2025-06-16T17:23:01.798Z (4 months ago)
- Topics: description, excerpt, file, hast, meta, rehype, rehype-plugin, summary, truncate
- Language: JavaScript
- Homepage: https://unifiedjs.com
- Size: 53.7 KB
- Stars: 13
- Watchers: 7
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: readme.md
- License: license
Awesome Lists containing this project
README
# rehype-infer-description-meta
[![Build][build-badge]][build]
[![Coverage][coverage-badge]][coverage]
[![Downloads][downloads-badge]][downloads]
[![Size][size-badge]][size]
[![Sponsors][sponsors-badge]][collective]
[![Backers][backers-badge]][collective]
[![Chat][chat-badge]][chat]
**[rehype][]** plugin to infer the description of a document.
## Contents
* [What is this?](#what-is-this)
* [When should I use this?](#when-should-i-use-this)
* [Install](#install)
* [Use](#use)
* [API](#api)
* [`unified().use(rehypeInferDescriptionMeta[, options])`](#unifieduserehypeinferdescriptionmeta-options)
* [`Options`](#options)
* [Types](#types)
* [Compatibility](#compatibility)
* [Security](#security)
* [Related](#related)
* [Contribute](#contribute)
* [License](#license)
## What is this?
This package is a [unified][] ([rehype][]) plugin to infer the description of a
document.
It supports different methods: a specific element, everything up to a comment,
or up to a certain number of characters.
**unified** is a project that transforms content with abstract syntax trees
(ASTs).
**rehype** adds support for HTML to unified.
**vfile** is the virtual file interface used in unified.
**hast** is the HTML AST that rehype uses.
This is a rehype plugin that inspects hast and adds metadata to vfiles.
## When should I use this?
This plugin is particularly useful in combination with
[`rehype-meta`][rehype-meta].
When both are used together, a `` is populated with the
document’s description.
## Install
This package is [ESM only][esm].
In Node.js (version 16+), install with [npm][]:
```sh
npm install rehype-infer-description-meta
```
In Deno with [`esm.sh`][esmsh]:
```js
import rehypeInferDescriptionMeta from 'https://esm.sh/rehype-infer-description-meta@2'
```
In browsers with [`esm.sh`][esmsh]:
```html
import rehypeInferDescriptionMeta from 'https://esm.sh/rehype-infer-description-meta@2?bundle'
```
## Use
Say our module `example.js` contains:
```js
import rehypeDocument from 'rehype-document'
import rehypeFormat from 'rehype-format'
import rehypeInferDescriptionMeta from 'rehype-infer-description-meta'
import rehypeMeta from 'rehype-meta'
import rehypeParse from 'rehype-parse'
import rehypeStringify from 'rehype-stringify'
import {unified} from 'unified'
const examples = [
// 1. Example where the description is in a certain element.
`
Hello, world!
Dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
`,
// 2. Example where the description runs from the start to a comment.
`Hello, world!
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
`,
// 3. Example where the description runs from the start to a certain number of characters.
`Hello, world!
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
`
]
const promises = examples.map(function (example) {
return (async function () {
const file = await unified()
.use(rehypeParse, {fragment: true})
.use(rehypeInferDescriptionMeta, {selector: '.byline'})
.use(rehypeDocument)
.use(rehypeMeta)
.use(rehypeFormat)
.use(rehypeStringify)
.process(example)
console.log(String(file))
})()
})
await Promise.all(promises)
```
…then running `node example.js` yields:
> 👉 **Note**: `meta[name="description"]` is derived from `.byline`:
```html
Hello, world!
Dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
```
> 👉 **Note**: `meta[name="description"]` is derived from content before ``:
```html
Hello, world!
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
```
> 👉 **Note**: `meta[name="description"]` is truncated from the document:
```html
Hello, world!
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
```
## API
This package exports no identifiers.
The default export is
[`rehypeInferDescriptionMeta`][api-rehype-infer-description-meta].
### `unified().use(rehypeInferDescriptionMeta[, options])`
Infer file metadata from the main title of a document.
The result is stored on `file.data.meta.description` (and
`file.data.meta.descriptionHast`).
###### Parameters
* `options` ([`Options`][api-options], optional)
— configuration
###### Returns
Transform ([`Transformer`][unified-transformer]).
###### Notes
The description is inferred through three strategies:
1. If `options.selector` is set and an element for that found, then the
description is the text of that element
2. Otherwise, if a comment is found with the text of `options.comment`, then
the description is the text up to that comment
3. Otherwise, the description is the text up to `options.truncateSize`
### `Options`
Configuration (TypeScript type).
###### Fields
* `comment` (`string`, default: `'more'`)
— string to look for in a comment; one of the strategies is to look for
this comment, everything before it is the description
* `ignoreSelector` (`string`, default: `'h1, script, style, noscript,
template'`)
— CSS selector of nodes to ignore; used when looking for an excerpt comment
or truncating the document
* `inferDescriptionHast` (`boolean`, default: `false`)
— whether to expose `file.data.meta.descriptionHast`; this is not used by
`rehype-meta`, but could be useful to other plugins; the value contains the
rich HTML elements rather than the plain text content
* `mainSelector` (`string`, optional)
— CSS selector to body of content; useful to exclude other things, such as
the head, ads, styles, scripts, and other random stuff, by focussing all
strategies in one element
* `maxExcerptSearchSize` (`number`, default: `2048`)
— how far to search for the excerpt comment before bailing; the goal of
explicit excerpts is that they are assumed to be somewhat reasonably
placed; this option prevents searching giant documents for some comment
that probably won’t be found at the end
* `selector` (`string`, optional)
— CSS selector to the description; one of the strategies is to look for a
certain element, useful if the description is nicely encoded in one element
* `truncateSize` (`number`, default: `140`)
— number of characters to truncate to; one of the strategies is to truncate
the document to a certain number of characters
## Types
This package is fully typed with [TypeScript][].
It exports the additional type [`Options`][api-options].
It also registers `file.data.meta` with `vfile`.
If you’re working with the file, make sure to import this plugin somewhere in
your types, as that registers the new fields on the file.
```js
/**
* @typedef {import('rehype-infer-description-meta')}
*/
import {VFile} from 'vfile'
const file = new VFile()
console.log(file.data.meta.description) //=> TS now knows that this is a `string?`.
```
## 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,
`rehype-infer-description-meta@^2`, compatible with Node.js 16.
This plugin works with `rehype-parse` version 3+, `rehype-stringify` version 3+,
`rehype` version 4+, and `unified` version 6+.
## Security
Use of `rehype-infer-description-meta` is safe.
## Related
* [`rehype-document`](https://github.com/rehypejs/rehype-document)
— wrap a fragment in a document
* [`rehype-meta`](https://github.com/rehypejs/rehype-meta)
— add metadata to the head of a document
* [`unified-infer-git-meta`](https://github.com/unifiedjs/unified-infer-git-meta)
— infer file metadata from Git
* [`rehype-infer-title-meta`](https://github.com/rehypejs/rehype-infer-title-meta)
— infer file metadata from the title of a document
* [`rehype-infer-reading-time-meta`](https://github.com/rehypejs/rehype-infer-reading-time-meta)
— infer file metadata from the reading time of a document
## Contribute
See [`contributing.md`][contributing] in [`rehypejs/.github`][health] for ways
to get started.
See [`support.md`][support] for ways to get help.
This project has a [code of conduct][coc].
By interacting with this repository, organization, or community you agree to
abide by its terms.
## License
[MIT][license] © [Titus Wormer][author]
[build-badge]: https://github.com/rehypejs/rehype-infer-description-meta/workflows/main/badge.svg
[build]: https://github.com/rehypejs/rehype-infer-description-meta/actions
[coverage-badge]: https://img.shields.io/codecov/c/github/rehypejs/rehype-infer-description-meta.svg
[coverage]: https://codecov.io/github/rehypejs/rehype-infer-description-meta
[downloads-badge]: https://img.shields.io/npm/dm/rehype-infer-description-meta.svg
[downloads]: https://www.npmjs.com/package/rehype-infer-description-meta
[size-badge]: https://img.shields.io/bundlejs/size/rehype-infer-description-meta
[size]: https://bundlejs.com/?q=rehype-infer-description-meta
[sponsors-badge]: https://opencollective.com/unified/sponsors/badge.svg
[backers-badge]: https://opencollective.com/unified/backers/badge.svg
[collective]: https://opencollective.com/unified
[chat-badge]: https://img.shields.io/badge/chat-discussions-success.svg
[chat]: https://github.com/rehypejs/rehype/discussions
[npm]: https://docs.npmjs.com/cli/install
[esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c
[esmsh]: https://esm.sh
[health]: https://github.com/rehypejs/.github
[contributing]: https://github.com/rehypejs/.github/blob/main/contributing.md
[support]: https://github.com/rehypejs/.github/blob/main/support.md
[coc]: https://github.com/rehypejs/.github/blob/main/code-of-conduct.md
[license]: license
[author]: https://wooorm.com
[rehype]: https://github.com/rehypejs/rehype
[rehype-meta]: https://github.com/rehypejs/rehype-meta
[typescript]: https://www.typescriptlang.org
[unified]: https://github.com/unifiedjs/unified
[unified-transformer]: https://github.com/unifiedjs/unified#transformer
[api-rehype-infer-description-meta]: #unifieduserehypeinferdescriptionmeta-options
[api-options]: #options