Using VSCode insiders: Jupyter Notebook Markdown Cell does not support \newcommand in Katex.

[chandresh]

Environment data

• VS Code version: 1.57.0-insider
• Jupyter Extension version (available under the Extensions sidebar): v2021.6.898847129
• Python Extension version (available under the Extensions sidebar): v2021.6.864643163-dev
• OS (Windows | Mac | Linux distro) and version: MacOS Big Sur 11.4
• Python and/or Anaconda version: 3.8.5
• Type of virtual environment used (N/A | venv | virtualenv | conda | ...): conda
• Jupyter server running: Local

I started using VSCode-insiders recently and loved the way new jupyter UI looks. But I noticed that two of the features that I used to use, does not work.

1. Global CSS for Markdown cells.
2. \newcommand in Katex

With VSCode

I usually add the common CSS and latex/katex newcommands on the the first markdown cell:

Then in any markdown cell, I am able to use those:

Here is the output:

With Insiders:

None of the above features work with VS Code Insiders:

Note 1: The CSS works if it is in the same cell. But that means I have to repeat all the needed CSS in each cell. \newcommand does not even work when defined in same cell.

Note 2: I found an issue which has some different problems with Insiders: microsoft/vscode-jupyter#6045.

[joyceerhl]

The \newcommand macro is supported in KaTeX (documentation). Here's a screenshot of math rendering correctly in the KaTeX demo playground:

Additionally, the \ra command is correctly registered and rendered in the new native notebooks interface if defined and used in the same equation block:

$$
\newcommand{\ra}{\rightarrow}

\ra
$$

So this may be due to the way that the markdown-it-katex plugin works.

[mjbvz]

One issue per issue please. Let's track \newcommand here since it more info about it has been posted

Please split the css issue to a separate issue

[chandresh]

@joyceerhl I will check if something is changed in markdown-it-katex plugin. I did not check in the same equation block, as it does not help much :) If I have to define it for every equation block that will become painful soon (thought might still be helpful for longer/complicated blocks). Ideally ability to define these in the first cell would be most useful (IMHO).

[chandresh]

@mjbvz Any chance that maybe this is somehow related to CSS related "block" you mentioned in the other issue: #125449 ?

[chrisyeh96]

KaTeX supports macros such as \newcommand if the macros are used within the same math block, such as

$$
    \newcommand{\ra}{\rightarrow}
    \ra
$$

By default, KaTeX does not "persist" the macros to new math blocks. However, [KaTeX has an option called "globalGroup"}(https://katex.org/docs/options.html) which enables KaTeX to persist such macros. I submitted a pull request #129747 which sets globalGroup: true. This should fix the issue.