Allow MathJax root to be configured. #1403

[dpvc]

Allow MathJax root to be configured. Resolves issue #1403.

The best way to set the root is to use

<script>
MathJax = {root:"http://myhost.net/mathjax"};
</script>
<script src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS_HTML"></script>

so that the configuration file will be loaded from the correct location as well. Otherwise, you can use

<script type="text/x-mathjax-config">
MathJax.Hub.Config({
  root:"http://myhost.net/mathjax",
  config: ["TeX-AMS_HTML.js"]
});
</script>
<script src="http://cdn.mathjax.org/mathjax/latest/MathJax.js"></script>

[zorkow]

Is Push synchronous, i.e., will there be a return value?

[dpvc]

Yes, the return value is the MathJax.Callback object created from the item pushed (Callbacks can be created from lots of possible data). The important point in returning the last callback pushed is that Callback objects are not only functions that can be called, but they also know how to work with MathJax.Callback.Queue objects; when a Callback is pushed on a Queue, the Queue will block until the Callback is called, and when it is, the next item in the Queue will start. But if a queued item returns another Callback, then the queue continues to pause until that callback is called, and so on.

So in this case, ConfigBlocks is itself pushed on a queue, and that queue will not continue until all the items that have been queued in queue in this routine are run, because the outer queue will have to wait for the Callback object returned by queue.Push(), and that only runs after everything else in queue has been run.

The MathJax.Callback was my attempt to do the job that now would be handled by promises, but that idea hadn't been developed (in javascript) at the time, and so the paradigm is a bit more awkward than it should be. It is one of the things that needs fixing in 3.0.

[zorkow]

Thanks for the explanation.
lgtm.