Allow using MathJax as a input filter for text formats, rather than a global filter

This is a much-needed feature.

Under Remaining Tasks, I also suggest we add: Read up on how to apply MathJax formatting to certain DOM elements (not globally).

Example module that creates an input filter.

I pushed a prototype to 7.x-2.x.

To test it, set up an input type with the MathJax filter and also set your MathJax configuration to:

MathJax.Hub.Config({
  extensions: ["tex2jax.js"],
  jax: ["input/TeX","output/HTML-CSS"],
  tex2jax: {
    inlineMath: [ ['$','$'], ['\\(','\\)'] ],
    processEscapes: true
  },
  showProcessingMessages: false,
  messageStyle: "none",
  elements: ['mathjax']
});

Known issues:
* This will work on only one DOM ID. This is because the Typeset() method by default wants a DOM ID, not a class.

See issue #2084267: Allow using MathJax as a input filter for text formats, rather than a global filter

This is a prototype of the idea. To test it, set up an input type with the MathJax filter and also set your MathJax configuration to:

MathJax.Hub.Config({
  extensions: ["tex2jax.js"],
  jax: ["input/TeX","output/HTML-CSS"],
  tex2jax: {
    inlineMath: [ ['$','$'], ['\\(','\\)'] ],
    processEscapes: true,
    processClass: "tex2jax",
    ignoreClass: "html"
  },
  showProcessingMessages: false,
  messageStyle: "none"
});

Known issues:
* None

This was done with the advice of Peter Krautzberger on the MathJax user group: https://groups.google.com/d/topic/mathjax-users/kGLtdrssYrg/discussion

The filter works as expected - with the patch attached, save the default MathJax configuration and create a text format using a MathJax filter.

The patch adds a missing comma to the MathJax configuration variable.

Thank you - patched.

Did you replace the MathJax configuration on the admin screen with this?:

MathJax.Hub.Config({
  extensions: ["tex2jax.js"],
  jax: ["input/TeX","output/HTML-CSS"],
  tex2jax: {
    inlineMath: [ ['$','$'], ['\\(','\\)'] ],
    processEscapes: true,
    processClass: "tex2jax",
    ignoreClass: "html"
  },
  showProcessingMessages: false,
  messageStyle: "none"
});

Let me think about that a while.

I think we need to either throw away the global option or offer a choice:

(*) Text filter: MathJax will be available as a text filter.
( ) MathJax runs globally.

By choosing either option, a default MathJax configuration will be placed into the admin form (by JS, I think), then the admin may edit.

7.x-2.0 beta

After testing the 7.x-2.x branch, using mathjax as a text format seems to work. The instructions are clear and work as expected.

Automated tests were failing in 7.x-2.x-beta1, those have been fixed in 7.x-2.x.