JavaScript provides powerful array iteration methods to work with elements easily. These methods help us write cleaner and shorter code.
1. forEach()
Executes a function for each element.
let nums = [1, 2, 3];
nums.forEach(n => console.log(n));
Output:
1
2
3
2. map()
Creates a new array by modifying each element.
let nums = [1, 2, 3];
let result = nums.map(n => n * 2);
console.log(result);
Output:
[2, 4, 6]
3. flatMap()
Maps and flattens the array.
let arr = [1, 2];
let result = arr.flatMap(x => [x, x * 2]);
console.log(result);
Output:
[1, 2, 2, 4]
4. filter()
Filters elements based on condition.
let nums = [1, 2, 3, 4];
let even = nums.filter(n => n % 2 === 0);
console.log(even);
Output:
[2, 4]
5. reduce()
Reduces array to a single value.
let nums = [1, 2, 3];
let sum = nums.reduce((acc, val) => acc + val, 0);
console.log(sum);
Output:
6
6. every()
Checks if all elements satisfy condition.
let nums = [2, 4, 6];
let allEven = nums.every(n => n % 2 === 0);
console.log(allEven);
Output:
true
7. some()
Checks if at least one element satisfies condition.
let nums = [1, 3, 4];
let hasEven = nums.some(n => n % 2 === 0);
console.log(hasEven);
Output:
true
8. Array.from()
Creates array from iterable.
let str = "hi";
let arr = Array.from(str);
console.log(arr);
Output:
[‘h’, ‘i’]
9. keys()
Returns array indices.
let arr = ["a", "b"];
console.log([...arr.keys()]);
Output:
[0, 1]
10. Spread Operator (…)
Expands array elements.
let arr = [1, 2];
let newArr = [...arr, 3, 4];
console.log(newArr);
Output:
[1, 2, 3, 4]
Reference
W3Schools
https://www.w3schools.com/js/js_array_iteration.asp