This is a Pascal compiler that targets WebAssembly, designed specifically to compile TeX so it can be run inside the browser. More specifically, this repository includes a TeX engine called jsTeX which is like LuaTeX but instead of embedding Lua it embeds JavaScript.
Importantly, the jsTeX engine passes the trip
tests
which you can verify by running make test.
There is a live demo and a short overview available at
J. Fowler, Both TEX and DVI viewers inside the web browser, TUGboat, Volume 40 (2019), No. 1.
This projects depends on NodeJS for
executing the javascript. To post-process the WebAssembly, you will
need wasm-opt on your path.
You will need a full TeX installation (e.g., TeX
Live) with access to kpsewhich in
order that library.js can find the necessary TeX files. You also
need tie and tangle to turn the WEB sources into Pascal which can
be fed to the compiler.
The contents of the texk, triptrap, and etexdir subdirectories
were copied from tug.org via
mkdir texk
rsync -a --delete --exclude=.svn tug.org::tldevsrc/Build/source/texk/web2c/tex.web texk
rsync -a --delete --exclude=.svn tug.org::tldevsrc/Build/source/texk/web2c/triptrap .
rsync -a --delete --exclude=.svn tug.org::tldevsrc/Build/source/texk/web2c/etexdir .
After cloning this repository, run npm install.
Then run
make core.dump
to apply the changefiles, compile the resulting Pascal source to
WebAssembly, and run initex.js to produce a format file and its
corresponding memory dump.
Then you can run TeX on a file called sample.tex with
node tex.js sample.tex
The main innovation of jsTeX is \directjs primitive similar to
LuaTeX's \directlua. For example,
\documentclass[12pt]{article}
\newcommand{\cubeit}[1]{\directjs{
tex.print('$');
tex.print(`#1^3 = ${#1*#1*#1}`);
tex.print('$');
}}
\begin{document}
Let's multiply eight by eight by eight. \cubeit{8}
\end{document}Inside \directjs, the JavaScript function tex.print can be used to
emit strings back into TeX for further processing.