How important is it to know JSON, Regular Expressions in Front-End?

Question

JavaScript

How much JSON and RegExp will be required in the frontend? Or is it more applicable in node.js and server side in general?
I don’t particularly do strong development, mostly theory and a little js, css, jquery practice.

Answer 1

It is necessary to know.
But json you "automatically" learn while learning JS, and regular expressions - in a few hours at a basic level sufficient for 90% of tasks.

Answer 2

RegExp is more likely to be needed.
The JSON syntax is based on javascript but is not fully compatible.
That is very important!