1. javascript
  2. /array methods
  3. /forEach

forEach() Array Method

The forEach() array method is a built-in method in JavaScript that allows you to iterate over an array and apply a callback function to each element in the array. This method is typically used to perform some action on each element in an array without the need for a for loop or other iteration construct.

Here is a quick example:

var numbers = [1, 2, 3, 4, 5];

numbers.forEach(function(number) {
  console.log(number);
});

We can use forEach() to iterate over the numbers array and instead of logging to console, we could theoretically do a calculation or perform another action on the items in the array.

Syntax and Parameters

array.forEach(function(element, index, array) {
  // code to be executed for each element
}, this);
ParameterDescriptionOptional/Required
functionThe callback function to be applied to each elementRequired
elementThe current element being processedRequired
indexThe index of the current element being processedOptional
arrayThe array that the forEach() method was called onOptional
thisDefaults to undefined. A value passed to the function as its this value.Optional

forEach() method examples:

Add a class to each element in an array:

var elements = document.querySelectorAll('div');

elements.forEach(function(element) {
  element.classList.add('highlight');
});

You may also want to check out:

map() filter() reduce()