remark-math-inline

A remark plugin for inline math using clean, unambiguous :math[...] syntax.

Why?

The standard $...$ syntax for inline math has problems:

• Ambiguity — $ conflicts with currency notation
• Poor parsing — Single $ delimiters are hard to parse reliably
• Tooling issues — Many Markdown parsers don't handle $ well

This plugin provides a cleaner alternative using explicit, directive-style syntax.

Install

npm install remark-math-inline

Usage

import { unified } from 'unified'
import remarkParse from 'remark-parse'
import remarkMathInline from 'remark-math-inline'
import remarkRehype from 'remark-rehype'
import rehypeKatex from 'rehype-katex'
import rehypeStringify from 'rehype-stringify'

const html = await unified()
  .use(remarkParse)
  .use(remarkMathInline)
  .use(remarkRehype)
  .use(rehypeKatex)
  .use(rehypeStringify)
  .process('The formula :math[E = mc^2] is famous.')

console.log(String(html))

Markdown Syntax

Inline math: :math[E = mc^2]

LaTeX commands work: :math[\alpha + \beta = \gamma]

Nested brackets are balanced: :math[f(x) = [a, b]]

Block Math

For display-mode math, use fenced code blocks with math language:

```math
\int_0^1 x^2 dx = \frac{1}{3}
```

This works out of the box with rehype-katex — no additional plugin needed.

Escaping

• \] → literal ] (doesn't close the math)
• \\ → literal \
• Other backslash sequences are preserved as-is (e.g., \alpha stays \alpha)

AST Node

The plugin creates inlineMath nodes compatible with rehype-katex:

interface InlineMath {
  type: 'inlineMath'
  value: string
  data: {
    hName: 'code'
    hProperties: { className: ['language-math', 'math-inline'] }
    hChildren: [{ type: 'text', value: string }]
  }
}

Adjacency

:math[...] must not be preceded by a word character. For adjacency without spaces, use parentheses:

mass(:math[m])     <!-- Works -->
mass:math[m]       <!-- Does NOT parse -->

Use with remark-directive

If you use both remark-math-inline and remark-directive, the plugin registered last takes precedence for :math[...] syntax.

// Math wins:
unified()
  .use(remarkDirective)
  .use(remarkMathInline)  // registered last

// Directive wins:
unified()
  .use(remarkMathInline)
  .use(remarkDirective)   // registered last

License

MIT