Post History

MathJax breaks in edit history

I noticed this in a [post on Code Golf Codidact] where MathJax is enabled.

The raw text of the post can be seen by pressing "Edit" or "Suggest edit" below the post:

![Text during editing, showing the $ enclosed MathJax terms](https://meta.codidact.com/uploads/agtvz9ibr166hhbzmzjjfc1rd3ph)

When viewing the edit history, most of the MathJax is rendered, rather than showing the raw text. However, a MathJax term that is partly edited shows as a mixture of rendered and raw text:

![Edit history, showing MathJax incorrectly rendered for parts that partly edited](https://meta.codidact.com/uploads/i5icw7t8lpoyo8d1gqyphx47a4qr)

This appears to be happening when the added or removed section of the edit separates the part of the text with the opening $ from the part of the text with the closing $. In the right hand green section in the screenshot above, there is an opening $ that is ignored by the renderer because its corresponding closing $ is inside the added section. That corresponding closing $ is then treated as an opening $, resulting in "*withthefirst*" being rendered as MathJax (it is between the closing $ of the MathJax term before, and the opening $ of the next MathJax term, and they are being treated as the opening and closing $ signs of a single MathJax term).

[post on Code Golf Codidact]: https://codegolf.codidact.com/posts/288516