@neos21/rehype-prism
rehype plugin to highlight code blocks in HTML with Prism (via refractor).
(If you would like to highlight code blocks with highlight.js, instead, check out rehype-highlight.)
Best suited for usage in Node. If you would like to perform syntax highlighting in the browser, you should look into less heavy ways to use refractor.
Installation
$ npm install @neos21/rehype-prismAPI
rehype().use(rehypePrism, [options])
Syntax highlights pre > code.
Under the hood, it uses refractor, which is a virtual version of Prism.
The code language is configured by setting a language-{name} class on the <code> element.
You can use any language supported by refractor.
If no language-{name} class is found on a <code> element, it will be skipped.
options
options.ignoreMissing
Type: boolean.
Default: false.
By default, if {name} does not correspond to a language supported by refractor an error will be thrown.
If you would like to silently skip <code> elements with invalid languages, set this option to true.
options.aliases
Type: object.
Default: undefined.
Register a new alias for the name language.
const unified = require('unified');
const remarkParse = require('remark-parse');
const remarkRehype = require('remark-rehype');
const rehypePrism = require('@neos21/rehype-prism');
const rehypeStringify = require('rehype-stringify');
const processor = unified()
.use(remarkParse)
.use(remarkRehype)
.use(rehypePrism, {
aliases: {
bash: 'sh',
markdown: 'mdown'
}
})
.use(rehypeStringify);Usage
Use this package as a rehype plugin.
Some examples of how you might do that:
const rehype = require('rehype');
const rehypePrism = require('@neos21/rehype-prism');
rehype()
.use(rehypePrism)
.process(/* some html */);const unified = require('unified');
const rehypeParse = require('rehype-parse');
const rehypePrism = require('@neos21/rehype-prism');
unified()
.use(rehypeParse)
.use(rehypePrism)
.processSync(/* some html */);If you'd like to get syntax highlighting in Markdown, parse the Markdown (with remark-parse), convert it to rehype, then use this plugin.
const unified = require('unified');
const remarkParse = require('remark-parse');
const remarkRehype = require('remark-rehype');
const rehypePrism = require('@neos21/rehype-prism');
unified()
.use(remarkParse)
.use(remarkRehype)
.use(rehypePrism)
.process(/* some markdown */);FAQ
Why does rehype-prism copy the language- class to the <pre> tag?
Prism recommends adding the language- class to the <code> tag like this:
<pre><code class="language-css">p { color: red }</code></pre>It bases this recommendation on the HTML5 spec. However, an undocumented behavior of their JavaScript is that, in the process of highlighting the code, they also copy the language- class to the <pre> tag:
<pre class="language-css"><code class="language-css"><span class="token selector">p</span> <span class="token punctuation">{</span> <span class="token property">color</span><span class="token punctuation">:</span> red <span class="token punctuation">}</span></code></pre>This resulted in many Prism themes relying on this behavior by using CSS selectors like pre[class*="language-"]. So in order for people using rehype-prism to get the most out of these themes, we decided to do the same.