How to break out of forEach in JavaScript

JavaScript added the forEach array method as part of ES5.

This function allows you to call a function on every single element in an array, essentially acting like a for loop.

However, because it is not a for loop but instead a function being run, you cannot use the break keyword with forEach.

In this post, we'll explore how you can mimic breaking out of a forEach method.

Break out of a forEach

Let's first look an example forEach loop by calling it on an array of numbers.

JAVASCRIPT
const numbers = [1, 2, 3, 4, 5];

numbers.forEach(number => {
    console.log(number);
});

Inside our forEach method, we are simply logging the value of the current element.

BASH
1
2
3
4
5

Let's say you wanted to stop after the third element.

As mentioned before, using break will not work with forEach.

JAVASCRIPT
const numbers = [1, 2, 3, 4, 5];

numbers.forEach(number => {
    console.log(number);

    if (number === 3) {
        break; // won't work
    }
});

Instead, you can try using a boolean as a flag. You can enable it whenever you want to break out of the loop.

JAVASCRIPT
const numbers = [1, 2, 3, 4, 5];

let flag = false;

numbers.forEach(number => {

    if (flag) {
        return;
    }
    
    if (number === 4) {
        flag = true;
        return;
    }
    
    console.log(number);
});

BASH
1
2
3

This functions correctly, but it is not very efficient because it is checking the flag every time.

However, this is about as good as we can get with a forEach loop, since as mentioned before, a method has to be called on every single element, no matter what.

In general, if you must break out of a loop, you should avoid using forEach and instead use a regular loop, however, it is still possible to simulate using break as shown above.

Conclusion

In this post, we've covered how to break out of a forEach loop by using a boolean flag.

It's not ideal but it's the best way to simulate a break keyword inside a forEach function.

Hopefully it helps you out and thanks for reading!

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