What is functional programming?

Functions in JavaScript are first-class objects, also known as “first-class citizens.” This means that we can work with functions in JavaScript

What is a pure function and how do we know if something is a pure function?

The definition of a pure function is: The function always returns the same result if the same arguments are passed in. It does not depend on any state, or data, change during a program’s execution. It must only depend on its input arguments

What are the benefits of a pure function?

One of the major benefits of using pure functions is they are immediately testable. They will always produce the same result if you pass in the same arguments. They also makes maintaining and refactoring code much easier

What is immutability?

In object-oriented and functional programming, an immutable object (unchangeable object) is an object whose state cannot be modified after it is created. This is in contrast to a mutable object (changeable object), which can be modified after it is created. In some cases, an object is considered immutable even if some internally used attributes change, but the object’s state appears unchanging from an external point of view. For example, an object that uses memoization to cache the results of expensive computations could still be considered an immutable object.

What is Referential transparency?

Referential transparency and referential opacity are properties of parts of computer programs. An expression is called referentially transparent if it can be replaced with its corresponding value (and vice-versa) without changing the program’s behavior. This requires that the expression be pure, that is to say the expression value must be the same for the same inputs and its evaluation must have no side effects. An expression that is not referentially transparent is called referentially opaque.