How to Use forEach in JavaScript: Syntax and Examples

In JavaScript, forEach is a method used to run a function on each item in an array. You call array.forEach(callback), where callback is a function that receives each item, its index, and the array itself.

Syntax

The forEach method calls a provided function once for each element in an array, in order.

• array: The array you want to loop through.
• callback: A function that runs on each element. It can take up to three arguments:
• element: The current item in the array.
• index (optional): The position of the current item.
• array (optional): The original array.

javascript

array.forEach(function(element, index, array) {
  // code to run on each element
});

Example

This example shows how to use forEach to print each fruit name with its position in the list.

javascript

const fruits = ['apple', 'banana', 'cherry'];
fruits.forEach((fruit, index) => {
  console.log(`${index + 1}: ${fruit}`);
});

Output

1: apple
2: banana
3: cherry

Common Pitfalls

One common mistake is trying to use forEach with return to stop the loop early, but forEach always runs on every element.

Also, forEach does not return a new array, so it is not suitable when you want to transform data.

javascript

const numbers = [1, 2, 3, 4];

// Wrong: trying to break out of forEach
numbers.forEach(num => {
  if (num === 3) {
    return; // only exits current callback, not the loop
  }
  console.log(num);
});

// Right: use a for loop to break early
for (const num of numbers) {
  if (num === 3) break;
  console.log(num);
}

Output

1
2
1
2

Quick Reference

• Use forEach to run code on each array item without creating a new array.
• Cannot break out of the loop early.
• Callback arguments: element, index, array.
• Does not return a value (returns undefined).

Key Takeaways

Use forEach to execute a function on every item in an array.

forEach callback receives element, index, and the whole array as arguments.

You cannot stop or break a forEach loop early; it always runs on all elements.

forEach does not return a new array or any value.

For transformations or early exit, use other methods like map or a for loop.