Support for MathJax 2.7.1 in a hakish way!

[OmarIthawi]

Open edX platform Ficus and beyond is using MathJax 2.7. So we need for the extension to support MathJax 2.7 as well.

The array hack caused the extension to partially break. Checkout my mathjax-dev post for more info.

The issue was introduced by: mathjax/MathJax#1523.

[OmarIthawi]

A non-production release v1.1-alpha have been created to demonstrate the bug.

[OmarIthawi]

I've added another hack to solve it. This needs to be fixed but I'm still not sure how, let's make it in a future release.

[dpvc]

Sorry for the delay in getting back to you. Hope this helps anyway.

Here is my recommendation. You don't want to set copyEnv = true because that will allow other things to bleed through to the table that shouldn't be. Instead, we want to copy the lang to the env after the array stack item is created. Ideally, that would be done in the Init() call, but because the env isn't set up until the array pushed onto the stack (and the Init() function doesn't have access to the stack), you can't do it then. Instead, you have to wait for it to be pushed on the stack. So my suggestion is overriding the stack's Push() function and transfer the lang if the pushed time is an array.

The following should do it.

MathJax.Hub.Register.StartupHook("TeX Jax Ready",function () {
  var STACK = MathJax.InputJax.TeX.Stack;
  var PUSH = STACK.prototype.Push;
  STACK.Augment({
    Push: function (item) {
      var lang = this.env.lang;
      PUSH.apply(this,arguments);
      if (lang && item instanceof STACK.Item.array) {
        this.env.lang = lang;
      }
    }
  });
  var CLEAR = STACK.Item.array.prototype.clearEnv;
  STACK.Item.Augment({
    clearEnv: function () {
      let lang = this.env.lang;
      CLEAR.call(this);
      if (lang) this.env.lang = lang;
    }
  });
});

This only copies the lang property, so doesn't bleed any other properties like copyEnv does.

Hope that helps.

[OmarIthawi]

No worries at all @dpvc. Yeah, I know that the I'm doing a terrible hack here, but it works for my basic test suite.

I'll create a test case for the environment bleed 🔪 that I've done. I'll use the code you've suggested to make sure it was fixed, then follow up with another release.

Thanks a lot!