JavaScript break

Summary: In this tutorial, you’ll learn how to use the JavaScript break statement to terminate a loop prematurely.

The label statement #

In JavaScript, you can label a statement for later use. Here’s the syntax of the label statement:

label: statement;

In this syntax, the label can be any valid identifier. For example, the following shows how to label a for loop using the outer label:

outer: for (let i = 0; i < 5; i++) {
    console.log(i);
}

Once you define a label, you can reference it in the break or continue statement.

Introduction to JavaScript break statement #

The break statement prematurely terminates a loop such as for, do...while, and while loop, a switch, or a label statement. Here’s the syntax of the break statement:

break [label];

In this syntax, the label is optional if you use the break statement in a loop or switch. However, if you use the break statement with a label statement, you need to specify it.

This tutorial focuses on how to use the break statement to terminate the loop prematurely.

Using the JavaScript break statement in a for loop #

The following for loop statement outputs five numbers from 0 to 4:

for (let i = 0; i < 5; i++) {
  console.log(i);
}

Try it

Output:

To terminate the for loop prematurely, you can use a break statement. For example, the following illustrates how to use a break statement inside a for loop:

for (let i = 0; i < 5; i++) {
  console.log(i);
  if (i == 2) {
    break;
  }
}

Try it

Output:

0
1
2

In this example, we use an if statement inside the loop. If the current value of i is 2, the if statement executes the break statement that terminates the loop.

This flowchart illustrates how the break statement works in a for loop:

Using the break statement to terminate a nested loop #

A nested loop has one loop inside another. For example, the following uses a nested for loop to output a pair of numbers from 1 to 3:

for (let i = 1; i <= 3; i++) {
  for (let j = 1; j <= 3; j++) {
    console.log(i, j);
  }
}

Try it

Output:

If you use a break statement inside an inner loop, it only terminates the enclosing loop. For example:

for (let i = 1; i <= 3; i++) {
  for (let j = 1; j <= 3; j++) {
    if (i + j == 4) {
      break;
    }
    console.log(i, j);
  }
}

Try it

Output:

1 1
1 2
2 1

In this example, if the sum of i and j is 4, the break statement terminates the inner loop. To terminate the nested loop, you use a label statement. For example:

outer: for (let i = 1; i <= 3; i++) {
  for (let j = 1; j <= 3; j++) {
    if (i + j == 4) {
      break outer;
    }
    console.log(i, j);
  }
}

Try it

Output:

1 1
1 2

In this example, we label the outer loop with the label outer. Inside the inner loop, we specify the outer label in the break statement. The break statement terminates the nested loop if the sum of i and j is 4.

Using the JavaScript break statement in a while loop #

The following output five numbers from 1 to 5 to the console using a while loop:

let i = 0;

while (i < 5) {
  i++;
  console.log(i);
}

Try it

Output:

Like a for loop, the break statement terminates a while loop prematurely. For example:

let i = 0;

while (i < 5) {
  i++;
  console.log(i);
  if (i == 3) {
    break;
  }
}

Try it

Output:

1
2
3

In this example, when the current value of i is 3, the break statement terminates the loop. Therefore, you see only three numbers in the output.

The following flowchart illustrates how the break statement works in a while loop:

Using the JavaScript break statement in a do…while loop #

The following example uses a do...while statement to output five numbers from 0 to 5 to the console:

let i = 0;

do {
  i++;
  console.log(i);
} while (i < 5);

Try it

Output:

Like a while loop, you can use a break statement to terminate a do...while loop. For example:

let i = 0;

do {
  i++;
  console.log(i);
  if (i == 3) {
    break;
  }
} while (i < 5);

Try it

Output:

1
2
3

The following flowchart shows how the break statement works in a do while loop:

Summary #

Use the break statement to terminate a loop including for, while, and do...while prematurely.
The break statement terminates the enclosing loop in a nested loop. To terminate the nested loop, you use a label statement.

Quiz #

Quiz

JavaScript break Statement

7 questions

To help you grasp the concept and usage of the break statement in JavaScript.

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