0.5.1 • Public • Published



A TeX/LaTeX validator.

texvcjs takes user input and validates it while replacing MediaWiki-specific functions. It is a JavaScript port of texvc, which was originally written in OCaml for the Math extension.

The texvcjs library was originally written to be used by the mw-ocg-latexer PDF-generation backend of the mediawiki Collection extension.

texvcjs also makes it possible to print the identified texvc tokens. Moreover, it provides additional information on the input such as

  • listing the identifiers;
  • discovering if the expressions ends with a dot.


Node version 10, 12 and 15 are tested to work.

Install the node package dependencies with:

npm install

Ensure everything works:

npm test


To test your installation:

bin/texvcjs '\sin(x)+{}{}\cos(x)^2 newcommand'

which should emit:


To test the info functionalities, run texvcjs with the info flag:

./bin/texvcjs --info -o json \\frac12 > ./vis/data.json


Your programs can also use the JavaScript API exported by the texvcjs node module:

var texvcjs = require('texvcjs');

var result = texvcjs.check('\\sin(x)+{}{}\\cos(x)^2 newcommand');
console.log(result.output || ''); // cleaned/validated output

If the output field is not undefined, then validation was successful.

The status field is a single character:

  • +: Success! The result is in the output field.
  • F: A TeX function was not recognized. The function name is in the details field.
  • S: A parsing error occurred.
  • -: Some other problem occurred.

For status types F, S, and -, the position of the error may be found in the line, column and offset fields of the result. More information about the problem can be found in the details field of the result, which is a string.

The fields ams_required, cancel_required, color_required, euro_required, and teubner_required are set to true iff the input string requires the use of the corresponding LaTeX packages. The ams_required field requires the use of the amsmath and amssymb packages.


To use the \ce tags from the mhchem package the parser needs to be called with the mhchem option. During the parsing if a \ce tag is encountered its contens is treated according to the mhchem grammar. The parsing in general and the building up of the AST is done in a similar fashion to the math mode but preserves the whitespaces when needed.

As the design of the parser does not allow the usage of the dollar sign in the math mode the tags \begin{math} and \end{math} were introduced to provide the ability to switch to math mode within a chemical formula. The undocumented \color tag of mhchem is only supported for named colors. The full documentation of the mhchem package can be found on the mhchem website.


This example would be typeset wrongly without the extended parser as some charges would be typeset as bonds and some addition signs would end up as charges. Running:

bin/texvcjs  --usemhchem '\ce{2Na + 2H2O -> 2Na+ + 2OH- + H-H}'


+{\ce {2Na + 2H2O -> 2Na+ + 2OH- + H-H}}

More examples can be found on the mhchem website.


Copyright (c) 2014-2022 C. Scott Ananian, Moritz Schubotz, Johannes Stegmüller

Licensed under GPLv2.


npm i mathoid-texvcjs

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