break

The break statement terminates the current loop or switch statement and transfers program control to the statement following the terminated statement. It can also be used to jump past a labeled statement when used within that labeled statement.

Syntax

break;
break label;

label
- : Identifier associated with the label of the statement to break to. If the break statement is not nested within a loop or switch, then the label identifier is required.

Description

When break; is encountered, the program breaks out of the innermost switch or looping statement and continues executing the next statement after that.

When break label; is encountered, the program breaks out of the statement labeled with label and continues executing the next statement after that. The break statement needs to be nested within the referenced label. The labeled statement can be any statement (commonly a block statement); it does not have to be another loop statement.

A break statement, with or without a following label, cannot be used at the top level of a script, module, function's body, or static initialization block, even when the function or class is further contained within a loop.

Examples

break in while loop

The following function has a break statement that terminates the while loop when i is 3, and then returns the value 3 * x.

function testBreak(x) {
  let i = 0;

  while (i < 6) {
    if (i === 3) {
      break;
    }
    i += 1;
  }

  return i * x;
}

break in switch statements

The following code has a break statement that terminates the switch statement when a case is matched and the corresponding code has run.

const food = "sushi";

switch (food) {
  case "sushi":
    console.log("Sushi is originally from Japan.");
    break;
  case "pizza":
    console.log("Pizza is originally from Italy.");
    break;
  default:
    console.log("I have never heard of that dish.");
    break;
}

break in labeled blocks

The following code uses break statements with labeled blocks. By using break outerBlock, control is transferred to the end of the block statement marked as outerBlock.

outerBlock: {
  innerBlock: {
    console.log("1");
    break outerBlock; // breaks out of both innerBlock and outerBlock
    console.log(":-("); // skipped
  }
  console.log("2"); // skipped
}

Unsyntactic break statements

A break statement must be nested within any label it references. The following code also uses break statements with labeled blocks, but generates a syntax error because its break statement references block2 but it's not nested within block2.

block1: {
  console.log("1");
  break block2; // SyntaxError: label not found
}

block2: {
  console.log("2");
}

Syntax errors are also generated in the following code examples which use break statements within functions that are nested within a loop, or labeled block that the break statements are intended to break out of.

function testBreak(x) {
  let i = 0;

  while (i < 6) {
    if (i === 3) {
      (() => {
        break;
      })();
    }
    i += 1;
  }

  return i * x;
}

testBreak(1); // SyntaxError: Illegal break statement

block1: {
  console.log("1");
  (() => {
    break block1; // SyntaxError: Undefined label 'block1'
  })();
}