How To Break Out Of A For Loop Javascript

In this tutorial, we will learn how to break out of a for loop in JavaScript. Sometimes, you might want to exit a loop before its iteration is complete, such as when a certain condition is met or a specific value is found. JavaScript provides a way to do this using the break statement.

Step 1: Creating a simple for loop

First, let’s create a simple for loop that iterates through an array of numbers.

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let numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
 
for (let i = 0; i < numbers.length; i++) {
    console.log(numbers[i]);
}

This code will print out all the elements in the numbers array.

Step 2: Using the break statement

Now, let’s say we want the loop to stop when the value 5 is found. We can do that using the break statement.

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for (let i = 0; i < numbers.length; i++) {
    if (numbers[i] === 5) {
        break;
}
console.log(numbers[i]);
}

When the loop encounters the break statement, it will immediately stop the current iteration and exit the loop. In this example, the output will only show the numbers 1 to 4, because the loop will exit when it reaches the number 5.

Step 3: Using break with labels

In some cases, you might have nested loops, and you might want to break out of more than one loop at a time. JavaScript allows you to do this using labels.

Consider the following example with nested loops:

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let matrix = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
];
 
outerLoop: for (let i = 0; i < matrix.length; i++) {
    for (let j = 0; j < matrix[i].length; j++) {
        if (matrix[i][j] === 5) {
            break outerLoop;
        }
        console.log(matrix[i][j]);
    }
 

Full Code:

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let numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
 
for (let i = 0; i < numbers.length; i++) {
    if (numbers[i] === 5) {
        break;
    }
    console.log(numbers[i]);
}
 
let matrix = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
];
 
outerLoop: for (let i = 0; i < matrix.length; i++) {
    for (let j = 0; j < matrix[i].length; j++) {
        if (matrix[i][j] === 5) {
            break outerLoop;
        }
        console.log(matrix[i][j]);
    }
}

Output:

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Conclusion

In this tutorial, we learned how to use the break statement to exit a for loop in JavaScript. We also looked at how to break out of nested loops using labels. The break statement can be a useful tool in controlling the flow of your loops and optimizing your code.