Skip to content

rehype plugin to highlight code blocks in HTML with Prism (via refractor) with line highlighting and line numbers

License

Notifications You must be signed in to change notification settings

timlrx/rehype-prism-plus

Folders and files

NameName
Last commit message
Last commit date

Latest commit

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Repository files navigation

rehype-prism-plus

sample-code-block-output

rehype plugin to highlight code blocks in HTML with Prism (via refractor) with additional line highlighting and line numbers functionalities.

Inspired by and uses a compatible API as @mapbox/rehype-prism with additional support for line-highlighting, line numbers and diff code blocks.

Tested to work with xdm and mdx v2 libraries such as mdx-bundler. If you are using mdx v1 libraries such as next-mdx-remote, you will need to patch it with the fixMetaPlugin discussed in this issue, before rehype-prism-plus.

An appropriate stylesheet should be loaded to style the language tokens, format line numbers and highlight lines. You can specify language for diff code blocks by using diff-[language] to enable syntax highlighting in diffs.

Installation

This package is ESM only: Node 12+ is needed to use it and it must be imported instead of required.

npm install rehype-prism-plus

Usage

The following import paths are supported:

  • rehype-prism-plus/generator, generator function. Can be used to generate a rehype prism plugin that works on your desired languages.
  • rehype-prism-plus/common, rehype plugin. Supports the languages in refractor/lib/common.js.
  • rehype-prism-plus/all, rehype plugin. Works with all language supported by refractor.
  • rehype-prism-plus, re-exports the above 3 packages with rehype-prism-plus/all as the default export.

Some examples of how you might use the rehype plugin:

import rehype from 'rehype'
import rehypePrism from 'rehype-prism-plus'

rehype().use(rehypePrism).process(/* some html */)

Here's an example of syntax highlighting in Markdown, with xdm

import { compile } from 'xdm'
import rehypePrism from 'rehype-prism-plus'

async function main(code) {
  console.log(String(await compile(code, { rehypePlugins: [rehypePrism] })))
}

main(`~~~js
console.log(1)
~~~`)

Sample markdown to HTML output

Input:

```js {1,3-4} showLineNumbers
function fancyAlert(arg) {
  if (arg) {
    $.facebox({ div: '#foo' })
  }
}
```

HTML Output:

<code class="language-js">
  <div class="code-line line-number highlight-line" line="1">
    <span class="keyword">function</span>
    <span class="function">fancyAlert</span><span class="punctuation">(</span
    ><span class="">arg</span><span class="punctuation">)</span>
    <span class="punctuation">{</span>
  </div>
  <div class="code-line line-number highlight-line" line="2">
    <span class="keyword">if</span>
    <span class="punctuation">(</span>arg<span class="punctuation">)</span>
    <span class="punctuation">{</span>
  </div>
  <div class="code-line line-number" line="3">
    $<span class="punctuation">.</span><span class="function">facebox</span
    ><span class="punctuation">(</span><span class="punctuation">{</span> div<span class="">:</span>
    <span class="string">'#foo'</span>
    <span class="punctuation">}</span><span class="punctuation">)</span>
  </div>
  <div class="code-line line-number" line="4">
    <span class="punctuation">}</span>
  </div>
  <div class="code-line line-number" line="5">
    <span class="punctuation">}</span>
  </div></code
>

Generating

To customise the languages for your own prism plugin:

import { refractor } from 'refractor/lib/core.js'
import markdown from 'refractor/lang/markdown.js'
import rehypePrismGenerator from 'rehype-prism-plus/generator'

refractor.register(markdown)
const myPrismPlugin = rehypePrismGenerator(refractor)

Styling

To style the language tokens, you can just copy them from any prismjs compatible ones. Here's a list of themes.

In addition, the following styles should be added for line highlighting and line numbers to work correctly:

pre {
  overflow-x: auto;
}

/**
 * Inspired by gatsby remark prism - https://www.gatsbyjs.com/plugins/gatsby-remark-prismjs/
 * 1. Make the element just wide enough to fit its content.
 * 2. Always fill the visible space in .code-highlight.
 */
.code-highlight {
  float: left; /* 1 */
  min-width: 100%; /* 2 */
}

.code-line {
  display: block;
  padding-left: 16px;
  padding-right: 16px;
  margin-left: -16px;
  margin-right: -16px;
  border-left: 4px solid rgba(0, 0, 0, 0); /* Set placeholder for highlight accent border color to transparent */
}

.code-line.inserted {
  background-color: rgba(16, 185, 129, 0.2); /* Set inserted line (+) color */
}

.code-line.deleted {
  background-color: rgba(239, 68, 68, 0.2); /* Set deleted line (-) color */
}

.highlight-line {
  margin-left: -16px;
  margin-right: -16px;
  background-color: rgba(55, 65, 81, 0.5); /* Set highlight bg color */
  border-left: 4px solid rgb(59, 130, 246); /* Set highlight accent border color */
}

.line-number::before {
  display: inline-block;
  width: 1rem;
  text-align: right;
  margin-right: 16px;
  margin-left: -8px;
  color: rgb(156, 163, 175); /* Line number color */
  content: attr(line);
}

Here's the styled output using the prism-night-owl theme:

sample-code-block-output

For more information on styling of language tokens, consult refractor and Prism.

API

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 or support line numbers and line highlighting for code blocks without a specified language, set this option to true.

options.defaultLanguage

Type: string. Default: ``.

Uses the specified language as the default if none is specified. Takes precedence over ignoreMissing.

Note: The language must be first registered with refractor.

options.showLineNumbers

Type: boolean. Default: false.

By default, line numbers will only be displayed for code block cells with a meta property that includes 'showLineNumbers'. To control the starting line number use showLineNumbers=X, where X is the starting line number as a meta property for the code block.

If you would like to show line numbers for all code blocks, without specifying the meta property, set this to true.

Note: This will wrongly assign a language class and the class might appear as language-{1,3} or language-showLineNumbers, but allow the language highlighting and line number function to work. An possible approach would be to add a placeholder like unknown so the div will have class="language-unknown"

About

rehype plugin to highlight code blocks in HTML with Prism (via refractor) with line highlighting and line numbers

Topics

Resources

License

Stars

Watchers

Forks

Sponsor this project

 

Packages

No packages published