Question

Javascript has a number of string manipulation operations which can be performed on it. So we have methods like concat(), slice(), match(), etc

My question is do all these string manipulation methods return a new string value as the result OR are there some methods which actually modify the actual string being used in the method ?

Answer 1

Strings in JavaScript (and many other languages) are implemented as immutable objects. This has a few beneficial properties:

1. It’s thread safe, and more specifically,
2. Multiple references to the same string can be kept safely without having to worry that the value changes.

This also means that all string methods must return a new string if they aim to modify the original value.