rehype plugin to infer the estimated reading time of a document.
Contents
What is this?
This package is a unified (rehype) plugin to infer the estimated reading time of a document. The estimation takes readability, calibrated relative to the target audience, into account.
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. When both are used together and documents are shared, the estimated reading time is shown on Slack or certain other services.
Install
This package is ESM only. In Node.js (version 16+), install with npm:
npm install rehype-infer-reading-time-meta
In Deno with esm.sh:
import rehypeInferReadingTimeMeta from 'https://esm.sh/rehype-infer-reading-time-meta@2'
In browsers with esm.sh:
<script type="module">
import rehypeInferReadingTimeMeta from 'https://esm.sh/rehype-infer-reading-time-meta@2?bundle'
</script>
Use
Say our module example.js contains:
import rehypeDocument from 'rehype-document'
import rehypeFormat from 'rehype-format'
import rehypeInferReadingTimeMeta from 'rehype-infer-reading-time-meta'
import rehypeMeta from 'rehype-meta'
import rehypeParse from 'rehype-parse'
import rehypeStringify from 'rehype-stringify'
import {unified} from 'unified'
const file = await unified()
.use(rehypeParse, {fragment: true})
.use(rehypeInferReadingTimeMeta)
.use(rehypeDocument)
.use(rehypeMeta, {twitter: true})
.use(rehypeFormat)
.use(rehypeStringify)
.process(
'<h1>Build</h1><p><strong>We provide the building blocks</strong>: from tiny, focussed, modular utilities to plugins that combine them to perform bigger tasks. And much, much more. You can build on unified, mixing and matching building blocks together, to make all kinds of interesting new things.</p>'
)
console.log(String(file))
…then running node example.js yields:
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta content="width=device-width, initial-scale=1" name="viewport">
<meta name="twitter:card" content="summary">
<meta name="twitter:label1" content="Reading time">
<meta name="twitter:data1" content="1 minute">
</head>
<body>
<h1>Build</h1>
<p><strong>We provide the building blocks</strong>: from tiny, focussed, modular utilities to plugins that combine them to perform bigger tasks. And much, much more. You can build on unified, mixing and matching building blocks together, to make all kinds of interesting new things.</p>
</body>
</html>
API
This package exports no identifiers. The default export is rehypeInferReadingTimeMeta.
Infer the estimated reading time from a document as file metadata.
The reading time is inferred not just on words per minute, but also takes readability into account. The result is stored on file.data.meta.readingTime.
Parameters
options (Options, optional) — configuration
Returns
Transform (Transformer).
Options
Configuration (TypeScript type).
Fields
age ([number, number] or number, default: [16, 18]) — target age group; this is the age your target audience was still in school; so, set it to 18 if you expect all readers to have finished high school, 21 if you expect your readers to be college graduates, etc; can be two numbers in an array to get two estimatesmainSelector (string, optional, example: 'main') — 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
Types
This package is fully typed with TypeScript. It exports the additional type 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.
/**
* @typedef {import('rehype-infer-reading-time-meta')}
*/
import {VFile} from 'vfile'
const file = new VFile()
console.log(file.data.meta?.readingTime) //=> TS now knows that this is a `([number, number] | number)?`.
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-reading-time-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-reading-time-meta is safe.
Contribute
See contributing.md in rehypejs/.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.
License
MIT © Titus Wormer