mhchem mathjax commands sometimes does not render properly

[edwar4rd]

Is this a hackmd.io issue?

• [x] Yes, the bug happens on https://hackmd.io
• [ ] No. If it's a self-hosted CodiMD instance, please fire up the issue in the repo of CodiMD: https://github.com/hackmdio/codimd

Read our Official tutorial

It's on https://hackmd.io/c/tutorials/

或是中文版 https://hackmd.io/c/tutorials-tw/

What's the problem

Current behaviour

Provide steps to reproduce:

1. Create a note
2. Add $\ce{H2O}$
3. Might or might not render the \ce command properly
4. Refresh (F5 or Ctrl+Shift+R) the page and it might/might not work

If possible, create a note with reproducible content and share the link with us.

https://hackmd.io/@edwar4rd/SyrEd-J46

Some older notes created by others are also broken

https://hackmd.io/@hikari/H1sVJtRy5

Expected behaviour

$\ce{H2O}$ should be displayed properly as a chemical formula with auto typesetting.

Environment

I use HackMD on:

Desktop

• OS: GNU/Linux
• Browser: Firefox
• Browser Version: 119.0 (64-bit)

Desktop

• OS: GNU/Linux
• Browser: Chromium
• Browser Version: 119.0.6045.123 (Official Build)

Desktop

• OS: Windows 11
• Browser: Firefox
• Browser Version: 119.0.1（64 位元）

Desktop

• OS: Windows 11
• Browser: Chrome
• Browser Version: 119.0.6045.124 (正式版本) (64 位元)

Mobile

• OS: Android 13; SM-A5360 Build/TP1A.220624.014
• Browser: Chrome
• Browser Version: 119.0.6045.66

Tested and reproducible (sometimes after a few page refresh) in all of the above environment.

Additional context

• Might be related to recent MathJax version bump
• Uncaught (in promise) TypeError: this.parent(...) is null error flood console
  • Uncaught (in promise) TypeError: Cannot read properties of null (reading 'replaceChild') when using Chromium/Chrome
• Sometimes it works sometimes it doesn't after page refresh
  • I've tried clearing cache multiple times
  • Maybe related to cdn cache?

[jackycute]

We have deployed a fix, now it should display properly. Feel free to keep us posted, thank you!

[edwar4rd]

Didn't test throughly but seem fixed. Thanks!