Array Iteration Methods in JavaScript 1. forEach() Executes a function for each element Does NOT return a new array let arr = [1, 2, 3]; arr.forEach(function(num) { console.log(num * 2); }); Output: 2 4 6 Use when you just want to print / perform action 2. map() let arr = [1, 2, 3]; let result = arr.map(num => num * 2); console.log(result); // [2, 4, 6] ✔ Use when you want to modify values 3. flatMap() Combines map() + flat() let arr = [1, 2, 3]; let result = arr.flatMap(num => [num, num * 2]); console.log(result); // [1,2,2,4,3,6] ✔ Use when returning arrays inside map 4. filter() Returns elements that match condition let arr = [1, 2, 3, 4]; let result = arr.filter(num => num % 2 === 0); console.log(result); // [2, 4] ✔ Use for selection 5. reduce()(To be discussed) let arr = [1, 2, 3, 4]; let sum = arr.reduce((acc, num) => acc + num, 0); console.log(sum); // 10 ✔ Use for sum, product, etc. 6. reduceRight()(To be discussed) let arr = ["a", "b", "c"]; let result = arr.reduceRight((acc, val) => acc + val); console.log(result); // "cba" 7. every() let arr = [2, 4, 6]; let result = arr.every(num => num % 2 === 0); console.log(result); // true 8. some() let arr = [1, 3, 4]; let result = arr.some(num => num % 2 === 0); console.log(result); // true 9. Array.from() let str = "hello"; let arr = Array.from(str); console.log(arr); // ["h","e","l","l","o"] 10. keys()(To be discussed) let arr = ["a", "b"]; for (let key of arr.keys()) { console.log(key); } Output: 0 1 11. entries() let arr = ["a", "b"]; for (let [index, value] of arr.entries()) { console.log(index, value); } Output: 0 a 1 b 12. with() let arr = [1, 2, 3]; let newArr = arr.with(1, 100); console.log(newArr); // [1,100,3] ✔ Does NOT modify original 13. Spread Operator(To be discussed) let arr1 = [1, 2]; let arr2 = [3, 4]; let result = [...arr1, ...arr2]; console.log(result); // [1,2,3,4] ✔ Used for copying, merging 14. Rest Operator ...(To be discussed) function sum(...nums) { return nums.reduce((a, b) => a + b); } console.log(sum(1, 2, 3)); // 6