latexjs / chktex.js

ChkTeX 1.7.6 for node environments

ChkTeX-JS

This is a lightly modified version of ChkTeX 1.7.6 that has been adapted to work inside a Node JS environment with Emscripten.

Building this code produces a single chktex.js Node module that is around 457kb (111kb compressed) that can be used interchangeably with chktex binaries. By that I mean:

> ./chktex.js -a -flag -or -two ./some/tex/file.tex

should perform identically to:

> chktex -a -flag -or -two ./some/tex/file.tex

If you find anything where this isn't true - it's a bug, please open an issue.

Prerequisites

• Emscripten SDK

Building

To build a release version of chktex.js just run

> ./build.sh

See the top of this script for more info (including how to make debug builds) if you run into issues.

FAQ

Why do this?

Well firstly it was a fun way to learn emscripten. :)

Secondly I'm a contributor to the LaTeX Workshop VS Code extension which includes rich ChkTeX support. This is an experiment to see if it would be possible to provide hassle-free LaTeX linting to all users by aiding them to install a version of chktex on their system if they don't already have it installed. This has the benefit that we can offer a consistent experience across platforms by helping users to download a 'binary' of chktex onto their system where we know it's up to date and works the same across platforms.

Can this be used in the browser?

Presently, no. For now I mapped through the FS access explicitly for Node (see Utility.h for details). This means we can offer a drop-in replacement for the existing chktex binary. For instance, by default chktex will follow other latex files included with \input{} and lint those also. This means chktex needs to call fopen of it's own valition and have something happen, which ain't happening in the browser sandbox.

However, chktex can be given input on stdin for a single file and you can disable following to other files with -I0. It would only be an hour or two's work to take this and get it working in the browser, and least for linting one file at a time.

How's the performance?

It's not bad. I actually discovered that at least on my MaxTeX install it seems chktex was compiled without optimizations! Given this, chktex.js is quite competitive linting my thesis:

> time node ~/gits/chktex-js/chktex.js thesis.tex > /dev/null
ChkTeX v1.7.6 - Copyright 1995-96 Jens T. Berger Thielemann.
Compiled with POSIX extended regex support.
No errors printed; 93 warnings printed; No user suppressed warnings; 92 line suppressed warnings.
See the manual for how to suppress some or all of these warnings/errors.

real	0m0.555s
user	0m0.709s
sys	0m0.042s

vs

> time chktex thesis.tex > /dev/null
ChkTeX v1.7.4 - Copyright 1995-96 Jens T. Berger Thielemann.
Compiled with POSIX extended regex support.
No errors printed; No warnings printed; No user suppressed warnings; 92 line suppressed warnings.

real	0m0.206s
user	0m0.172s
sys	0m0.013s

So, within a factor of two.

That's all folks!

Now follows is the original README of ChkTeX:

ChkTeX

ChkTeX is a tool to check for common errors in LaTeX files. It also supports checking CWEB files (uses a perl5 script). It is highly customizable allowing you turn off any warnings you don't like, as well as add your own warnings. It works easily with Emacs and AUCTeX, but should also be easy to interface with other editors. If you have interfaced ChkTeX with another editor, please contribute how you did it.

It is important to remember that ChkTeX is only intended as a guide to fixing faults. It is by no means always correct. This means that correct LaTeX code may produce errors in ChkTeX, and vice versa: incorrect LaTeX code may pass silently through. If you have ideas for new warnings or ways in which current warnings could be improved, please report them on the bug tracker.

For complete documentation see the manual.

ChkTeX is released under the GNU Public License version 2 or greater.