.. _node-main:

################################## Experimenting with MathJax in Node ##################################

If you want to experiment with MathJax in node, that is not hard to do using the approach described below. Note that this approach can not be used in a browser, but only for server-side or command-line applications. If you plan to bundle your MathJax code for use in a larger browser-based application, you will need to use one of the other methods described in the :ref:node-start section.

First :ref:get a copy of the MathJax code library <obtain-mathjax>. Here, we will assume you have used npm or pnpm to install the @mathjax/src@4 package. You will need to change the require() or import statements accordingly in the examples below if you have loaded mathjax@4 or obtained MathJax from the MathJax-src GitHub repository.

.. _node-first-program:

Your First MathJax Program

Create a file named :file:test-mathjax.mjs containing the following:

.. code-block:: javascript

import MathJax from "@mathjax/src"; await MathJax.init({loader: {load: ['input/tex']}}); const mml = (await MathJax.tex2mmlPromise('x+y')); console.log(mml);

then run this file from the command line using

.. code-block:: shell

node test-mathjax.mjs

It should produce the output

.. code-block::

This is you first MathJax node program!

.. note::

You could perform the same function from a CommonJS file rather than an ES6 module by creating :file:test-mathjax.cjs containing

.. code-block:: javascript

  const MathJax = require("@mathjax/src");
  MathJax.init({
    loader: {load: ['input/tex']}
  }).then(() => MathJax.tex2mmlPromise('x+y'))
    .then((mml) => console.log(mml));

then run this file using

.. code-block:: shell

 node test-mathjax.cjs

The :meth:init() function above takes as its argument a MathJax configuration object just like the ones used to configure MathJax in a browser. (See the :ref:configuring-mathjax pages for more details.) It returns a promise that is resolved when MathJax has loaded the needed components and is ready to process mathematics, at which point the global :js:data:MathJax variable will be set up for use.

In the program above, we use the await command to wait for that promise to resolve, and then wait for the :js:meth:MathJax.tex2mmlPromise() call to convert a TeX or LaTeX expression into the corresponding MathML tree. The result is then printed.

Once you have initialized MathJax, you should be able to use MathJax in much the same way as you would in a browser. Note, however, that stand-alone node applications don't have a browser DOM, so don't have a :js:data:window or :js:data:document variable. Because of this, MathJax in node doesn't produce DOM elements, but rather uses its own liteDOM replacement for the browser DOM. See :ref:node-DOM-adaptor section for more details about how you interact with the liteDOM.

.. _node-main-source:

Loading MathJax from Source

The examples above load MathJax from the bundled versions in the @mathjax/src/bundle directory, which are the files that would be used if you obtained MathJax from a server in a web page viewed by a browser. It is possible to use MathJax from the source .js files instead, however; for example, if you are making changes to the MathJax source code and want to check it quickly without having to repack your whole project.

To do so, use either

.. code-block:: javascript

import MathJax from '@mathjax/src/source';

or

.. code-block:: javascript

const MathJax = require('@mathjax/src/source');

when loading MathJax.

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