JavaScript Array forEach() Method

The JavaScript Array forEach() method is a built-in function that executes a provided function once for each array element. It does not return a new array and does not modify the original array. It's commonly used for iteration and performing actions on each array element.

Syntax

array.forEach(callback(element, index, arr), thisValue);

Parameters

This method accept five parameters as mentioned above and described below:

Return value

It does not return a new array. It returns undefined. This method may or may not change the original array provided as it depends upon the functionality of the argument function.

Example 1: Basic iteration to print array elements on console.

const arr = [1, 2, 3, 4, 5];

arr.forEach((item) => {
    console.log(item);
});

1
2
3
4
5

Example 2: Copy every element from one array to another array using Array.forEach() method.

// JavaScript Array forEach() Method

// Original array
const items = [12, 24, 36];
const copy = [];

items.forEach(function (item) {
    copy.push(item);
});

console.log(copy);

[ 12, 24, 36 ]

Example 3: Calculates the square of every element of the array using forEach() method.

// JavaScript Array forEach() Method

// Original array
const items = [1, 29, 47];
const squareOfItems = [];

items.forEach(function (item) {
    squareOfItems.push(item * item);
});

console.log(squareOfItems);

[ 1, 841, 2209 ]

Limitations of forEach() Method

• No Break or Continue: Unlike for loops, you cannot break the forEach() loop or use continue to skip to the next iteration. It will always iterate over all elements.
• No Return Value: The forEach() loop does not return a new array, it returns undefined.
• Asynchronous Issues: The forEach() loop does not handle asynchronous operations well. If you need to perform asynchronous operations, consider using for...of with async/await or Promise.all.

Supported Browsers

• Google Chrome
• Edge 
• Firefox
• Opera
• Safari