MathJax in Go (GoJax?)

[RPGillespie6]

This project is awesome. We were looking to reduce/eliminate our dependency on Node.js in order to minimize our go-based web application's SBOM/CVE surface area. However, latex rendering was a thorny issue that was tricky to get around. We currently use MathJax with Node.js for rendering latex to svg (the go application invokes node). First we tried switching to go-latex, but unfortunately it was not mature enough (and seems abandoned). So we tried running MathJax directly in a goja VM, and with a few adaptors to mock some DOM-related stuff, it worked perfectly!

Best of all, no discernible performance impact when generating svgs from latex.

In case it helps anyone else, here's a MathJax bundle file template you can use to load into goja:

import { MathJax } from "@mathjax/src/mjs/components/global.js";
import { insert } from "@mathjax/src/mjs/util/Options.js";
import "@mathjax/src/mjs/components/startup.js";
import "@mathjax/src/components/mjs/core/core.js";
import "@mathjax/src/components/mjs/adaptors/liteDOM/liteDOM.js";
import "@mathjax/src/components/mjs/input/tex-base/tex-base.js";
import "@mathjax/src/components/mjs/input/tex/extensions/ams/ams.js";
import "@mathjax/src/components/mjs/input/tex/extensions/newcommand/newcommand.js";
import "@mathjax/src/components/mjs/input/tex/extensions/textcomp/textcomp.js";
import "@mathjax/src/components/mjs/output/svg/svg.js";
import { MathJaxTexFont } from "@mathjax/mathjax-tex-font/mjs/svg.js";

insert(
    MathJax.config,
    {
        tex: {
            packages: { "[+]": ["ams", "newcommand", "textcomp"] },
        },
        svg: {
            fontData: MathJaxTexFont,
        },
    },
    false
);
MathJax.config.startup.ready();
globalThis.__tex2svg = function (texString) {
    const svg = MathJax.tex2svg(texString, { display: true });
    return MathJax.startup.adaptor.outerHTML(svg);
};

Build with:

# Can optionally move the banner to banner.js and make it first import instead
npx esbuild entry.mjs --minify --bundle --platform=neutral --format=iife \
    --banner:js='if(typeof URL==="undefined"){globalThis.URL=function(u){this.pathname=u||"/mathjax"};}' \
    --outfile=./mathjax_bundle.js

You can then add this to your go:

//go:embed mathjax_bundle.js
var mathjaxBundle string

And now your go code can render latex by directly running MathJax in a goja VM!

Thanks again for this project!