What is functional programming?

Functional programming is a programming paradigm that is based on the concept of functions. In functional programming, functions are treated as first-class citizens, which means that they can be passed around as arguments to other functions, returned as values from functions, and stored in variables. This approach emphasizes the use of pure functions, which do not have side effects and always return the same output for a given input.

One of the key benefits of functional programming is that it allows for more concise, readable, and maintainable code. By breaking down a problem into smaller functions, it becomes easier to reason about the code and debug it. Functional programming also enables easier parallelization and concurrency, since pure functions can be executed independently without affecting the state of other parts of the program.

JavaScript has many features that support functional programming, such as higher-order functions, closures, and anonymous functions.

Higher-order functions are functions that take other functions as arguments or return functions as values.

Closures are functions that have access to variables in their outer scope, even after the outer function has returned.

Anonymous functions are functions that do not have a name and can be defined inline.

These features allow for the creation of powerful and flexible functions that can be composed and reused in a variety of contexts.