It’s one of the core principles of web development and it means that you should Choose the least powerful language suitable for a given purpose.
On the web this means preferring HTML over CSS, and then CSS over JS. JS is the most versatile language out of the three because you’re the one describing how the browser should act, but it can also break, it can fail to load and it takes extra resources to download, parse and run. It is also very easy to exclude keyboard users and people using assistive technologies with it.
Kilian Valkhof - “You don’t need JavaScript for that”