.. _debugging-tips:

**********************
MathJax Debugging tips
**********************

This page documents basic tips for debugging MathJax in your application.


Using unpacked resources
========================

MathJax provides both packged (minified) and unpacked versions of all its components. For debugging, it is useful to switch to an unpacked versions.

For example, using a CDN just add `unpacked/` before `MathJax.js`, e.g., from


.. code-block:: html

    <script type="text/javascript" async
      src="https://example.com/MathJax.js?config=TeX-MML-AM_CHTML">
    </script>

to


.. code-block:: html

    <script type="text/javascript" async
      src="https://cdn.mathjax.org/mathjax/latest/unpacked/MathJax.js?config=TeX-MML-AM_CHTML">
    </script>


Getting traceback information
=============================

.. code-block:: javascript

  MathJax.Hub.lastError


MathJax stores the error object from the last `Math Processing Error` in `MathJax.Hub.lastError`. This allow developers to access the stack trace information when needed.


Add listener for MathJax errors
===============================

MathJax provides a detailed signaling infrastructure which a developers can hook into.

The following example hooks into Math Processing Errors.

.. code-block:: javascript

  MathJax.Hub.Register.MessageHook("Math Processing Error",function (message) {
    //  do something with the error.  message[2] is the Error object that records the problem.
  });


Another example hooks into TeX parsing errors.

.. code-block:: javascript

  MathJax.Hub.Register.MessageHook("TeX Jax - parse error",function (message) {
    // do something with the error.  message[1] will contain the data about the error.
  });

.. note::

  For more information, see :ref:`mathjax-api`.