Summary:
This adds support for rendering KaTeX to both HTML and MathML
with the intent of improving accessibility. To accomplish this, both
MathML and HTML are rendered, but with the MathML visually hidden and
the HTML spans aria-hidden. Hopefully, this should produce much better
accessibility for KaTeX.
Should fix/improve #38Closes#189
Test Plan:
- Ensure all the tests, and the new tests, still pass.
- Ensure that for each of the group types in `buildHTML.js`, there is a
corresponding one in `buildMathML.js`.
- Ensure that the huxley screenshots didn't change (except for
BinomTest, which changed because I fixed a bug in `buildHTML` where
`genfrac` didn't have a `groupToType` mapping).
- Run ChromeVox on the test page, render some math. (for example,
`\sqrt{x^2}`)
- Ensure that a mathy-sounding expression is read. (I hear "group
square root of x squared math").
- Ensure that nothing else is read (like no "x" or "2").
- Ensure that MathML markup is generated correctly and is interpreted
by the browser correctly by running
`document.getElementById("math").innerHTML =
katex.renderToString("\\sqrt{x^2}");` and seeing that the same speech
is read.
Reviewers: john, alpert
Reviewed By: john, alpert
Subscribers: alpert, john
Differential Revision: https://phabricator.khanacademy.org/D16373
