Maybe I should mention that a red backslash is shown in the not working cases instead of producing whitespace.

So the "working" cases seem to produce a space while the "non-working" cases produces a no-break space  . That can be fixed easily by adding a .replace(/\u00A0/g," ") in ConvertMath of wiki2jax, or making the PHP output a space or by fixing bug 35479 and removing the wiki2jax processor.

See also upstream issue https://github.com/mathjax/MathJax/issues/377

physik wrote:

It still causes problems see
https://de.wikipedia.org/wiki/Benutzer:Physikerwelt#BUG_49210

@Physikerwelt have you tried what Fred Wang suggested above? (Or do you need a volunteer to code it so that you can land it?)

This is a bad interaction between the math extension (or perhaps MediaWiki more generally, I don't know) and MathJax "bug" 377.

MediaWiki converts <math>x\ :</math> to <math>x\&nbsp; :</math>. While MathJax tolerates &nbsp; in TeX source code, it interprets "\&nbsp;" a TeX command -- invisible hilarity ensues...

You could argue that if MathJax considers &nbsp; a space, then it should tolerate \&nbsp; as well. I'll raise this on our issue tracker (I've reopened the bug).

Peter.

There will be a fix for this in the next MathJax version, see https://github.com/mathjax/MathJax/issues/377

physik wrote:

I'll provide a guide how to cherry pick patches from MathJax to Wikipedia.

physik wrote:

Renderes fine in MathML mode
see
https://www.mediawiki.org/wiki/Extension:Math/bug/49210

Well, it was basically a MathJax bug, but that seems fixed, too (so the bug is really resolved).