@mdit/plugin-katex

Plugins to render math expressions with KaTeX.

Note

This plugin is based on @mdit/plugin-tex.

Usage Node.js runtime only

import MarkdownIt from "markdown-it";
import { katex } from "@mdit/plugin-katex";

const mdIt = MarkdownIt().use(katex);

mdIt.render("$E=mc^2$");

const MarkdownIt = require("markdown-it");
const { katex } = require("@mdit/plugin-katex");

const mdIt = MarkdownIt().use(katex);

mdIt.render("$E=mc^2$");

We also have a package called @mdit/plugin-katex-slim which katex is an optional peer.

Syntax

You should use $tex expression$ inline, and use $$tex expression$$ for block.

Style

You should import katex/dist/katex.min.css from katex package or CDN yourself.

Escaping

You can use \ to escape $:
```
Euler’s identity \$e^{i\pi}+1=0$
```
will be
Euler’s identity $e^{i\pi}+1=0$

Demo

Euler’s identity $e^{i π} + 1 = 0$ is a beautiful formula in $R^{2}$ .

\frac{\partial^{r}}{\partial ω^{r}} (\frac{y^{ω}}{ω}) = (\frac{y^{ω}}{ω}) {(\log y)^{r} + \sum_{i = 1}^{r} \frac{(- 1)^{I} r \dots (r - i + 1) (\log y)^{r i}}{ω^{i}}}

Euler’s identity $e^{i\pi}+1=0$ is a beautiful formula in $\mathbb{R}^2$.

$$
\frac {\partial^r} {\partial \omega^r} \left(\frac {y^{\omega}} {\omega}\right)
= \left(\frac {y^{\omega}} {\omega}\right) \left\{(\log y)^r + \sum_{i=1}^r \frac {(-1)^ Ir \cdots (r-i+1) (\log y)^{ri}} {\omega^i} \right\}
$$

mhchem extension

If you want to load the mhchem extension, you should import loadMhchem from @mdit/plugin-katex:

import { loadMhchem } from "@mdit/plugin-katex";

await loadMhchem();

Since it's async, you should call it in prepare stage as markdown-it rendering is sync.

Options

type KatexLogger<MarkdownItEnv = unknown> = (
  errorCode:
    | "unknownSymbol"
    | "unicodeTextInMathMode"
    | "mathVsTextUnits"
    | "commentAtEnd"
    | "htmlExtension"
    | "newLineInDisplayMode",
  errorMsg: string,
  token: Token,
  env: MarkdownItEnv,
) => "error" | "warn" | "ignore" | boolean | undefined | void;

type TeXTransformer = (content: string, displayMode: boolean) => string;

interface MarkdownItKatexOptions<MarkdownItEnv = unknown> extends KatexOptions {
  /**
   * Whether to allow inline math with spaces on ends
   *
   * @description NOT recommended to set this to true, because it will likely break the default usage of $
   *
   * @default false
   */
  allowInlineWithSpace?: boolean;

  /**
   * Whether parsed fence block with math language to display mode math
   *
   * @default false
   */
  mathFence?: boolean;

  /**
   * Error logger
   */
  logger?: KatexLogger<MarkdownItEnv>;

  /**
   * transformer on output content
   */
  transformer?: TeXTransformer;
}

Support List

Cookbook

$T E X$ Cookbook