JavaScript Array forEach() Method (original) (raw)
Last Updated : 02 Sep, 2024
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:
| Parameter | Description |
|---|---|
| callback | It is a callback function executes on each array element. |
| element | The current element being processed in the array. |
| index (Optional) | The index of current element. The array indexing starts from 0. |
| array (Optional) | The array on which forEach() is called. |
| thisArg (Optional) | Value to use as this when executing the callback function. |
**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.
JavaScript `
const arr = [1, 2, 3, 4, 5];
arr.forEach((item) => { console.log(item); });
`
**Example 2: Copy every element from one array to another array using **Array.forEach() method.
JavaScript `
// JavaScript Array forEach() Method
// Original array const items = [12, 24, 36]; const copy = [];
items.forEach(function (item) { copy.push(item); });
console.log(copy);
`
**Example 3: Calculates the square of every element of the array using **forEach() method.
JavaScript `
// JavaScript Array forEach() Method
// Original array const items = [1, 29, 47]; const squareOfItems = [];
items.forEach(function (item) { squareOfItems.push(item * item); });
console.log(squareOfItems);
`
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.