rehype plugin to highlight code blocks in HTML with Prism

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rehype plugin to highlight code blocks in HTML with Prism (via refractor) fork from mapbox/rehype-prism.
(If you would like to highlight code blocks with highlight.js, instead, check out rehype-highlight.)


npm install rehype-prism-template


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.



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.


Type: array. Default: undefined
By default, the full list of languages supported by refractor will be registered.
If you would like to include specific languages, set this option to an array of languages.


Use this package as a rehype plugin.
Some examples of how you might do that:
const rehype = require('rehype');
const rehypePrism = require('rehype-prism-template');

  .process(/* some html */);

const unified = require('unified');
const rehypeParse = require('rehype-parse');
const rehypePrism = require('rehype-prism-template');

  .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('rehype-prism-template');

  .process(/* some markdown */);

Registering languages

By default rehype-prism-template includes all language definitions from refractor, though it's possible to set your custom list of registered languages by generating a new template of index.js. It is as easy as going in the package's root directory and specifing a list of languages:
cd /node_modules/rehype-prism
yarn register python java ruby kotlin

To reset the template back where it registers all languages:
yarn register-all


Why does rehype-prism copy the language- class to the <pre> tag?
Prism recommends adding the language- class to the <code> tag like this:
p { color: red }
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:
p { color: red }
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.