Understand String Immutability
Javascript String is immutable, which means once a String object is assigned to String reference the object value cannot be changed. However, we can still assign a new object to a String reference.
What is mutable and immutable String in JavaScript? Mutable is a type of variable that can be changed. In JavaScript, only objects and arrays are mutable, not primitive values. A mutable object is an object whose state can be modified after it is created. Immutables are the objects whose state cannot be changed once the object is created.