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 con