On sites with MathJax enabled, e.g. Astronomy, Physics and Aviation (thanks @NogShine), hovering over the tags doesn't display the excerpt and statistics anymore. The tag does get highlighted when you hover over it:

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Tested on macOS 10.13.3 with the latest Safari and Firefox. Sites without MathJax, including Meta Stack Exchange, are not affected:

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As @ShadowWizard notes, the problem is caused by the JavaScript file necessary to render MathJax.

  • 1
    Aviation also.
    – Nog Shine
    Mar 29, 2018 at 7:58
  • 1
    Uncaught TypeError: Cannot read property 'toLowerCase' of undefined. Mar 29, 2018 at 8:03
  • I get a different error upon hovering: TypeError: c.nodeName is undefined[Learn More]
    – Glorfindel Mod
    Mar 29, 2018 at 8:04
  • The above client side error occurs in Tex-Latex related file, so it means tags popup won't work on any site with Tex-Latex enabled Mar 29, 2018 at 8:04
  • Yep, Math.SE is affected as well.
    – Glorfindel Mod
    Mar 29, 2018 at 8:05
  • Marc (Gravell) is on top of this, hopefully he'll hunt the bug down soon and fix it. Mar 29, 2018 at 8:27
  • @ShadowWizard wait... I said I'd take a look; you may be grossly misunderstanding my UI/javascript skills :) Mar 29, 2018 at 8:28
  • @Marc heh... I have faith in you. Worst case scenario, you see who committed the change with the bug and poke them with a sharp stick until they fix the bug. ;) Mar 29, 2018 at 8:31

1 Answer 1


This will be fixed in the next build rev 2018.3.29.29636 or greater.

The tag hover menu code was passing a jQuery object (instead of the underlying DOM element it was wrapping) to MathJax.Hub.Typeset.

I've also bumped MathJax to the latest minor version (2.7.2 -> 2.7.3).

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