This example shows how to produce MathML output from MathJax's TeX
input, without the need for a native MathML output jax. We do this by
defining a new renderAction that replaces the usual
output jax's typesetting operation; its job is to create the usual
mjx-container node and set its innerHTML to
the serialzied version of the internal MathML produced by MathJax.
We use MathJax.startup.document.convertPromise, the
function that underlies the functions like `MathJax.tex2mmlPromise()`
in order to obtain the container node, and when the promise resolves,
we simply insert that container into the page and tell the menu code
that it is there (since we don't have an output jax to do that for
us). Using the promise-based convertion function allows for the
possibility that they use \require to load extensions
dynamically, or one is loaded automatically by the
autoload extension.
When the user presses the Render TeX button or
switches the display checkbox or one of the other
controls, the Interactive.convert() function runs. The
comments in the code explain how the conversion process is
handled. Note that the user interface is disabled during the
typesetting process, since the conversion is done asynchronously in
this example. This prevents the user from starting a new typeset
operation while one is already in progress.
Most browser only implement MathML-Core, a limited version of
MathML that doesn't include all the features that MathJax uses. In
particular, MathML-Core doesn't include the mathvariant
attribute that MathJax uses to implement commands like `\mathbf`,
`\mathbb`, and so on, so using MathJax MathML output directly may mean
that some font variants may not show up properly here. The
Convert mathvariants checkbox will enable code that
converts the characters within elements that use
mathvariant attributes into their counterparts in the
Math Alphanumerics uncide block, as required by MathML-Core. Note,
however, that not all characters have such counterparts, so you may
not be able to generate a bold plus sign or an italic number, for
example, as there are no unicode equivalents for those. When this
occurs, we add a style attribute as a fall-back to get
the proper variant, when possible.
The code for doing the mathvariant conversion is in a
separate mml-core.js script.