v3 fails to handle equal sign in Unicode.

[w32zhong]

MathJax v3 demo page has issue rendering this formula containing an Unicode equal sign:

$\sum_{k＝1}$

The error message is

Cannot read property 'parentNode' of null

I am not sure if the demo page is using some outdated version or does this issue still exist in latest version.

[dpvc]

The issue stems from the fact that your equal sign is form the full-width character range, and the MathJax fonts don't include that character. That means MathJax needs to try to measure the character in the browser, since it has no metric information for it. The demonstration you link to is an illustration of the MathJax.tex2chtml() function, which calls the convert() function internally. That converts a TeX string to DOM elements without the need for the string to be in the document itself. But when MathJax needs to measure unknown characters, it must insert it into the document to do so. MathJax inserts the character in the document at the location of the original math string, but in the case of convert(), there is no such location, and that is what is leading to this error.

I have made a pull request that allows convert() to handle unknown characters without throwing an error.