etoolboxjax

This MathJax extension ports LaTeX counters, the \numexpr command, and commands from the LaTeX etoolbox package to MathJax, including

• boolean flags (both bools and toggles);
• tests for
  • macros,
  • counters,
  • strings, and
  • arithmetic; and
• list processing.

Installation

This extension only supports MathJax v4. To use this extension, clone this repository and build the extension:

git clone https://github.com/evfinkn/etoolboxjax
cd etoolboxjax
# pnpm is used here, but npm can be used instead.
pnpm install
pnpm run build

This will create a browser folder containing the counter and etoolbox extensions. (counter can be used independently of etoolbox, but etoolbox depends on counter.) Then, include the extensions in your MathJax configuration:

MathJax = {
  loader: {
    load: ["[browser]/counter.js", "[browser]/etoolbox.js"],
    paths: { browser: "./browser" },
  },
  tex: {
    packages: { "[+]": ["counter", "etoolbox"] },
  },
};

Usage

A simple example of how to use counters for section numbering is shown below.

<span style="display: hidden;">\[
  \newcounter{section} \newcounter{subsection}
  \counterwithin{subsection}{section} % Reset subsection counter at each section
  \newcommand{\section}{\stepcounter{section} \thesection}
  \newcommand{\subsection}{\stepcounter{subsection} \thesubsection}
\]</span>

<h1>Section \(\section\)</h1> <!-- Section 1 -->
<h2>Subsection \(\subsection\)</h2> <!-- Subsection 1.1 -->
<h2>Subsection \(\subsection\)</h2> <!-- Subsection 1.2 -->

<h1>Section \(\section\)</h1> <!-- Section 2 -->
<!-- ... -->

For a more in-depth example of counter usage, see here.

An example of using the etoolbox package is shown below.

\newcounter{sum}
\newcommand{\do}[1]{\addtocounter{sum}{\numexpr{#1 * #1}}}
\docsvlist{1,2,3,4,5}
\thesum % 55