MathJax VS CodeMirror

Developer tools point to MathJax https://www.mathjax.org/. If you disable javascript you can see some LaTex.

It is something we could add, but it is not planned in the near future. We also have requests for adding math notation (like https://www.mathjax.org/), and that could be a more general solution.

I don't know what Obsidian is, but if it's requiring old TeX math mode toggles (the double dollar sign), then it might not actually be using LaTeX underneath. Many tools that provide LaTeX-style syntax for equations are actually using something like MathJaX, BlahTex, or some custom system by which to translate LaTeX-like syntax into their own equation rendering. This often means you only get a pre-defined subset of what's possible with LaTeX (and the results are never quite faithful to how LaTeX would typeset them).

This will depend heavily on where you're asking the question, e.g. stackexchange has built in mathjax to render it. I'm going to assume you're intending to ask here (because that would make sense), in which case check out the bottom of the sidebar.

From the screenshot, Obsidian looks like a typical Markdown editor that supports some LaTeX math syntax, probably rendered with something like Mathjax. On the other hand, Xournalapp seems to actually use LaTeX, even allowing you to use LaTeX packages like graphicx, tikz, etc.

codemirror - a code editor component for the web

massCode uses Codemirror as the basis for the editor and .tmLanguage as the grammar for syntax highlighting. This tandem opens the door to over 600 existing grammars. The application currently supports more than 160 grammars. In addition to .tmLanguage, the application supports .tmTheme for themes. There is also…

After giving up countless times since I started this project, I finally managed to dig the dark secrets of Pyodide and run pyTermTk on a browser, all of this, of course, thanks to the magic of xterm.js. I know, my friend, I know what you are thinking, I was disgusted at first picturing that hideous javascript defiling the python purity of my code, but, when I saw my red pepper shining on webkit engine, well, I couldn't hold back a tear. And after that, who am I to not include also an editor and my collection of demos and examples? So, here it is, a super minimal buggy and feature incomplete pyTermTk Sandbox

syntax highlighting is simple with https://codemirror.net/

Can CodeMirror 2 be used to highlight code from a DIV or PRE tag (without the editor)?

Official website of Codemirror.

CodeMirror [MIT] https://codemirror.net/

There sure is, take a look at Code Mirror

Codemirror is open source, so you can look at, clone and experiment with its actual code as much as you like to figure out how it works.

Developed using the LAMP stack mainly because I'm more of a back-end (PHP) dev, and for various other reasons, like affordable web servers. The front-end is vanilla JavaScript (AJAX for dynamic stuff). I also use CodeMirror to provide the visual-code editor for programmers.