This project is a monorepo that contains several packages for dealing with math in markdown and HTML.

• What is this?
• When should I use this?
• Examples
  • Example: KaTeX
  • Example: MathJax
• Security
• Contribute
• License

This repository contains unified (rehype and remark) plugins to add support for math. You can use them to add support for parsing and serializing a syntax extension and to render math with KaTeX or MathJax.

• remark-math — remark plugin to support a math syntax in markdown
• rehype-katex — rehype plugin to render math in HTML with KaTeX
• rehype-mathjax — rehype plugin to render math in HTML with MathJax

When dealing with markdown, you optionally use remark-math, or alternatively use fenced code (```math). Then, you either use rehype-katex or rehype-mathjax to render math in HTML.

This project is useful when you want to support LaTeX math. This mechanism works well when you want authors, that have some LaTeX experience, to be able to embed rich diagrams of math to scientific documentation. The extra syntax extension supported by remark-math for math in markdown does not work everywhere so it makes markdown less portable. This project is also useful as it renders math with KaTeX or MathJax at compile time, which means that there is no client side JavaScript needed.

Say our document example.md contains:

Lift($$L$$) can be determined by Lift Coefficient ($$C_L$$) like the following
equation.

$$
L = \frac{1}{2} \rho v^2 S C_L
$$

…and our module example.js contains:

import rehypeKatex from 'rehype-katex'
import rehypeStringify from 'rehype-stringify'
import remarkMath from 'remark-math'
import remarkParse from 'remark-parse'
import remarkRehype from 'remark-rehype'
import {read} from 'to-vfile'
import {unified} from 'unified'

const file = await unified()
  .use(remarkParse)
  .use(remarkMath)
  .use(remarkRehype)
  .use(rehypeKatex)
  .use(rehypeStringify)
  .process(await read('example.md'))

console.log(String(file))

…then running node example.js yields:

<p>Lift(<code class="language-math math-inline"><span class="katex">…</span></code>) like the following
equation.</p>
<pre><code class="language-math math-display"><span class="katex-display"><span class="katex">…</span></span></code></pre>

👉 Note: KaTeX requires CSS to render correctly. Use katex.css somewhere on the page where the math is shown to style it properly:

<!-- Get the latest one from: https://katex.org/docs/browser -->
<link href="https://cdn.jsdelivr.net/npm/[email protected]/dist/katex.min.css" rel="stylesheet">

Supporting either MathJax or KaTeX is very similar. Take the above KaTeX example and change:

@@ -1,4 +1,4 @@
-import rehypeKatex from 'rehype-katex'
+import rehypeMathjax from 'rehype-mathjax'
 import rehypeStringify from 'rehype-stringify'
 import remarkMath from 'remark-math'
 import remarkParse from 'remark-parse'
@@ -10,7 +10,7 @@ const file = await unified()
   .use(remarkParse)
   .use(remarkMath)
   .use(remarkRehype)
-  .use(rehypeKatex)
+  .use(rehypeMathjax)
   .use(rehypeStringify)
   .process(await read('example.md'))

…then running node example.js yields:

<p>Lift(<mjx-container class="MathJax" jax="SVG"><!--…--></mjx-container>) can be determined by Lift Coefficient (<mjx-container class="MathJax" jax="SVG"><!--…--></mjx-container>) like the following
equation.</p>
<mjx-container class="MathJax" jax="SVG" display="true"><!--…--></mjx-container><style>
mjx-container[jax="SVG"] {
  direction: ltr;
}
/* … */
</style>

Assuming you trust KaTeX/MathJax, using rehype-katex/rehype-mathjax is safe. If a vulnerability is introduced in them, it opens you up to a cross-site scripting (XSS) attack. See their readmes for more info.

See contributing.md in remarkjs/.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.

MIT © Junyoung Choi and TANIGUCHI Masaya