JSLaTeX

Supercharging LaTeX with JavaScript through EJS/ETS (embedded TypeScript!)

Note: Instead of <% and %> tags, JSLaTeX uses <? and ?> in order maintain compatibility with existing LaTeX tools such as LaTeX formatters (since the % symbol is treated as comments in LaTeX).

Installation

To install the JSLaTeX compiler, run:

npm install --global jslatex

Usage

To compile a LaTeX file with EJS/ETS, run:

jslatex <file>

For example, if your LaTeX file was named chem.tex, you would run:

jslatex chem.tex

This would produce a file in the same directory called chem.out.tex. Because the outputted LaTeX document is pure LaTeX, it can be passed to standard LaTeX tools, like latexmk or lualatex.

If you want to specify the name of the output file, you can use the -o or --out option:

jslatex chem.tex -o compiled-chem.tex

Example

The following chem.tex file (syntax highlighting provided by the JSLaTeX VSCode extension):

Gets compiled by JSLaTeX into the following LaTeX code:

\documentclass{article}
\usepackage[margin=1in]{geometry}
\usepackage{float}
\usepackage{tabularx}
\usepackage{ragged2e}
\usepackage[version=4]{mhchem}



\begin{document}
  \begin{table}[H]
    \begin{tabularx}{\linewidth}{|
        >{\RaggedRight}X|
        >{\RaggedRight}X|
        >{\RaggedRight}X|
        >{\RaggedRight}X|
        >{\RaggedRight}X|
        >{\RaggedRight}X|
      }
      \hline
      Trial \#
      & Volume of \ce{CuSO4} /mL
      & Baseline temperature /$^{\circ}$C
      & Time of \ce{Zn} addition /s
      & Equation of cooling line
      & R value
      \\\hline

        1
        & 20
        & 24.4
        & 72
        & -0.042 - 0.042$x$
        & -0.992
        \\\hline

        2
        & 20
        & 24.2
        & 132
        & -0.052 - 0.052$x$
        & -0.959
        \\\hline

        3
        & 20
        & 24.2
        & 60
        & -0.086 - 0.086$x$
        & -0.993
        \\\hline

        4
        & 20
        & 24.8
        & 72
        & -0.005 - 0.005$x$
        & -0.951
        \\\hline

        5
        & 20
        & 24.6
        & 96
        & -0.042 - 0.042$x$
        & -0.996
        \\\hline

        6
        & 20
        & 23.1
        & 14
        & 0.006 + 0.006$x$
        & 0.952
        \\\hline

        7
        & 20
        & 23.8
        & 15
        & -0.060 - 0.060$x$
        & -0.897
        \\\hline

        8
        & 20
        & 24.6
        & 96
        & -0.029 - 0.029$x$
        & -0.997
        \\\hline

    \end{tabularx}
  \end{table}
\end{document}

Note that there is no trace of the original JavaScript code in the final LaTeX file.

This LaTeX can then be compiled by a standard LaTeX compiler like pdflatex or lualatex to produce the following PDF file:

You can also use imports within EJS:

\documentclass{article}

<? const { default: cowsay } = await import('cowsay') ?>

\begin{document}
\begin{verbatim}
<?# Using the cowsay package from https://www.npmjs.com/package/cowsay ?>
<?= cowsay.say({ text: 'LaTeX!' }) ?>
\end{verbatim}
\end{document}

The above JSLaTeX code gets compiled to:

\documentclass{article}



\begin{document}
\begin{verbatim}

 ________
< LaTeX! >
 --------
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||
\end{verbatim}
\end{document}

And when compiled with a standard LaTeX compiler, the corresponding output PDF will display the following:

Programmatic Usage

You can import JSLaTeX as a regular npm package and call it from Node.js:

import { compileJsLatex, compileJsLatexFile } from 'jslatex';

const result = await compileJsLatex(String.raw`
\documentclass{article}
<?= "Hello from EJS!" ?>
`);

console.log(result);
// Outputs:
/*
\documentclass{article}
Hello from EJS!
*/

// In order for dynamic `import()`s to work, you need to pass projectBaseUrl:
console.log(
  await compileJsLatexFile({
    filePath: 'cow.tex',
    projectBaseUrl: import.meta.url,
  })
);