JavaScript Array Methods: Complete Guide (map, filter, reduce, and More)

JavaScript arrays are the backbone of nearly every application you'll write. But knowing which array method to reach for — and how to chain them efficiently — is what separates clean, expressive code from verbose, bug-prone loops. This guide covers every modern JavaScript array method with working examples you can run directly in your browser console. The Core Iteration Methods Array.prototype.map() map() creates a new array by transforming each element through a callback function. The original array is never modified. It's the right choice any time you want to convert every item in a collection. const prices = [10, 25, 50, 100]; const withTax = prices.map(price => price * 1.08); console.log(withTax); // [10.8, 27, 54, 108] // Transforming objects const users = [ { id: 1, name: 'Alice', role: 'admin' }, { id: 2, name: 'Bob', role: 'user' }, ]; const names = users.map(u => u.name); console.log(names); // ['Alice', 'Bob'] // Map with index const indexed = ['a', 'b', 'c'].map((item,