rehype-picture

rehype-picture

rehype plugin to wrap images in pictures.

Contents

• What is this?
• When should I use this?
• Install
• Use
• API
  • unified().use(rehypePicture[, options])
  • Options
  • Sources
• Types
• Compatibility
• Security
• Contribute
• License

What is this?

This package is a unified (rehype) plugin to change images (<img>) into pictures (<picture>). This lets you use a single image source in your content which is then automatically turned into a picture with several sources.

unified is a project that transforms content with abstract syntax trees (ASTs). rehype adds support for HTML to unified. hast is the HTML AST that rehype uses. This is a rehype plugin that changes images in the tree.

When should I use this?

This plugin is useful when you have the same images in different file formats. For example, when you have a build step that generates alternative image files (say, .webps) from source files (say, .jpgs). Then, when you link to the source images, you can use this plugin to generate the markup for both.

Install

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

npm install rehype-picture

In Deno with esm.sh:

import rehypePicture from 'https://esm.sh/rehype-picture@5'

In browsers with esm.sh:

<script type="module">
  import rehypePicture from 'https://esm.sh/rehype-picture@5?bundle'
</script>

Use

import rehypeParse from 'rehype-parse'
import rehypePicture from 'rehype-picture'
import rehypeStringify from 'rehype-stringify'
import {unified} from 'unified'

const file = await unified()
  .use(rehypeParse, {fragment: true})
  .use(rehypePicture, {
    jpg: {webp: 'image/webp'},
    png: {svg: 'image/svg+xml'}
  })
  .use(rehypeStringify)
  .process('<img src="cat.jpg">\n<img src="logo.png">')

console.log(String(file))

Yields:

<picture><source srcset="cat.webp" type="image/webp"><img src="cat.jpg"></picture>
<picture><source srcset="logo.svg" type="image/svg+xml"><img src="logo.png"></picture>

API

This package exports no identifiers. The default export is rehypePicture.

unified().use(rehypePicture[, options])

Wrap images in pictures.

Parameters

• options (Options, optional) — configuration

Returns

Transform (Transformer).

Options

Configuration (TypeScript type)

Maps file extensions (without dot, so such as jpg) to sources.

Type

type Options = Record<string, Sources | null | undefined>

Sources

Sources (TypeScript type)

Maps file extensions (without dot, so such as webp) to mime types.

Type

type Sources = Record<string, string | null | undefined>

Types

This package is fully typed with TypeScript. It exports the additional types Options and Sources.

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-picture@^5, 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

Although this plugin should be safe to use, be careful with user input images as it’s often possible to hide JavaScript inside them (such as GIFs, WebPs, and SVGs). User provided images open you up to a cross-site scripting (XSS) attack.

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