TypeScript Array forEach()
Syntax & Examples

Array.forEach() method

The forEach() method executes a provided function once for each array element. It does not return a value.

Syntax of Array.forEach()

The syntax of Array.forEach() method is:

forEach(callbackfn: function, thisArg?: any): void

This forEach() method of Array performs the specified action for each element in an array.

Parameters

ParameterOptional/RequiredDescription
callbackfnrequiredA function to execute for each element, taking three arguments: the current element, the index of the current element, and the array being traversed.
thisArgoptionalValue to use as this when executing callbackfn.

Return Type

Array.forEach() returns value of type void.


✐ Examples

1 Using forEach() to iterate over an array

The forEach() method can be used to iterate over each element of an array and perform a specified action.

For example,

  1. Create an array arr with numeric values [1, 2, 3, 4, 5].
  2. Define a callback function that logs each element to the console.
  3. Use forEach(callbackfn) to execute the callback function for each element in the array.

TypeScript Program

const arr = [1, 2, 3, 4, 5];
arr.forEach(element => console.log(element));

Output

1
2
3
4
5

2 Using forEach() to modify array elements

The forEach() method can be used to modify each element in an array.

For example,

  1. Create an array arr with numeric values [1, 2, 3, 4, 5].
  2. Define a callback function that multiplies each element by 2 and logs the result to the console.
  3. Use forEach(callbackfn) to execute the callback function for each element in the array.

TypeScript Program

const arr = [1, 2, 3, 4, 5];
arr.forEach(element => console.log(element * 2));

Output

2
4
6
8
10

3 Using forEach() with index and array parameters

The forEach() method can be used with a callback function that takes the current element, index, and array as parameters.

For example,

  1. Create an array arr with string values ['a', 'b', 'c'].
  2. Define a callback function that logs the current element and its index to the console.
  3. Use forEach(callbackfn) to execute the callback function for each element in the array.

TypeScript Program

const arr = ['a', 'b', 'c'];
arr.forEach((element, index) => console.log(`Element: ${element}, Index: ${index}`));

Output

Element: a, Index: 0
Element: b, Index: 1
Element: c, Index: 2

Summary

In this TypeScript tutorial, we learned about forEach() method of Array: the syntax and few working examples with output and detailed explanation for each example.