Functional Programming in Javascript

What is functional programming?

a programming paradigm — a style of building the structure and elements of computer programs — that treats computation as the evaluation of mathematical functions and avoids changing-state and mutable data.

Pure Functions

• functions that are determinsitic; returns the same value when given same arguments, and have no side effects (modifying a global object or a parameter passed by reference)

• Any function that relies on a random number generator cannot be pure

• mutability is discouraged in functional programming.

• When data is immutable, its state cannot change after it’s created. If you want to change an immutable object, you can’t. Instead, you create a new object with the new value.

• pure functions + immutable data = referential transparency

Refactoring JavaScript for Performance and Readability

There are no absolutes when it comes to clean code — there’s always an edge case.

• when refactoring code, keep readability, efficiency, and less repetition in mind.
• throwing an error can be useful for handling unexpected scenarios/errors so as to avoid getting undefined values.