What is functional programming in JavaScript?

What is functional programming in JavaScript?

Functional programming is a programming paradigm that treats computation as the evaluation of mathematical functions. In JavaScript, it emphasizes the use of pure functions, higher-order functions, and immutability.

Can you give me an example of a pure function?

Sure! A pure function is one that, given the same input, will always return the same output and has no side effects. For example:

function add(a, b) {
    return a + b;
}

What are higher-order functions?

Higher-order functions are functions that can take other functions as arguments or return them as results. For example:

function map(array, callback) {
    let result = [];
    for (let i = 0; i < array.length; i++) {
        result.push(callback(array[i]));
    }
    return result;
}

How does immutability work in JavaScript?

Immutability means that once a data structure is created, it cannot be changed. In JavaScript, you can achieve immutability using methods like Object.freeze() or by using libraries like Immutable.js.