JavaScript Array forEach() Method

The arr.forEach() method calls the provided function once for each element of the array. The provided function may perform any kind of operation on the elements of the given array. 

Syntax:

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

Parameters:

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

• callback: This parameter holds the function to be called for each element of the array.
• element: The parameter holds the value of the elements being processed currently.
• index: This parameter is optional, it holds the index of the current value element in the array starting from 0.
• array: This parameter is optional, it holds the complete array on which Array.every is called.
• thisArg: This parameter is optional, it holds the context to be passed as this is to be used while executing the callback function. If the context is passed, it will be used like this for each invocation of the callback function, otherwise undefined is used as default.

Return value:

The return value of this method is always undefined. This method may or may not change the original array provided as it depends upon the functionality of the argument function. 

Example 1: In this example, the Array.forEach() method is used to copy every element from one array to another.

JavaScript

// JavaScript to illustrate forEach() method
function func() {

  // Original array
  const items = [12, 24, 36];
  const copy = [];
  items.forEach(function (item) {
    copy.push(item + item + 2);
  });
  console.log(copy);
}
func();

Output

[ 26, 50, 74 ]

Example 2: In this example, the method forEach() calculates the square of every element of the array.

JavaScript

// JavaScript to illustrate forEach() method
function func() {

  // Original array
  const items = [1, 29, 47];
  const copy = [];
  items.forEach(function (item) {
    copy.push(item * item);
  });
  console.log(copy);
}
func();

Output

[ 1, 841, 2209 ]

Supported Browsers:

• Google Chrome 1 and above
• Edge 12 and above
• Firefox 1.5 and above
• Internet Explorer 9 and above
• Opera 9.5 and above
• Safari 3 and above

We have a complete list of JavaScript Array methods, to check those please go through the Javascript Array Complete Reference article.