The break statement in JavaScript is used to terminate a loop, switch, or in conjunction with a labeled statement.

Syntax

break;

Break in Loops

In loops, the break statement ends the loop entirely and moves the execution to the line of code immediately following the loop.

Here’s an example:

for (let i = 0; i < 10; i++) {
  if (i === 5) {
    break;
  }
  console.log(i);
}

In this example, the loop will terminate when i equals 5, so the numbers 0 through 4 will be logged to the console.

Break in Switch Statement

In a switch statement, break is used to prevent the “fallthrough” behavior of switch statements, where all cases are evaluated until a break is encountered or the switch statement ends.

Here’s an example:

let fruit = 'Apple';

switch (fruit) {
  case 'Apple':
    console.log('Apple is ₹ 32');
    break;
  case 'Banana':
    console.log('Banana is ₹ 48');
    break;
  default:
    console.log('Invalid fruit');
    break;
}

In this example, once a match is found and its code is executed, the break statement prevents the rest of the cases from being checked.

Break with Labeled Statement

A label is simply an identifier followed by a colon (:) that is applied to a statement or a block of code. The break statement, when used with a label, allows you to break out to any other place in your code.

Here’s an example:

let x = 0;
let z = 0;
labelCancelLoops: while (true) {
  console.log('Outer loops: ' + x);
  x += 1;
  z = 1;
  while (true) {
    console.log('Inner loops: ' + z);
    z += 1;
    if (z === 10 && x === 10) {
      break labelCancelLoops;
    } else if (z === 10) {
      break;
    }
  }
}

In this example, break labelCancelLoops; statement breaks the outer loop labeled labelCancelLoops.

The break statement in JavaScript provides you with a lot of control over the flow of your code. It allows you to optimize your code and make it more readable and efficient.