break

The break statement terminates the current loop, switch, or label statement and transfers program control to the statement following the terminated statement.

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Syntax

break [label];

label

Optional. Identifier associated with the label of the statement. If the statement is not a loop or switch, this is required.

Description

The break statement includes an optional label that allows the program to break out of a labeled statement. The break statement needs to be nested within the referenced label. The labeled statement can be any block statement; it does not have to be preceded by a loop statement.

A break statement, with or without a following label, cannot be used within the body of a function that is itself nested within the current loop, switch, or label statement that the break statement is intended to break out of.

Examples

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) {
  var i = 0;

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

  return i * x;
}

The following code uses break statements with labeled blocks. A break statement must be nested within any label it references. Notice that inner_block is nested within outer_block.

outer_block: {
  inner_block: {
    console.log('1');
    break outer_block; // breaks out of both inner_block and outer_block
    console.log(':-('); // skipped
  }
  console.log('2'); // skipped
}

The following code also uses break statements with labeled blocks, but generates a Syntax Error because its break statement is within block_1 but references block_2. A break statement must always be nested within any label it references.

block_1: {
  console.log('1');
  break block_2; // SyntaxError: label not found
}

block_2: {
  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) {
  var i = 0;

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

return i * x;
}

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

block_1: {
  console.log('1');
  ( function() {
    break block_1; // SyntaxError: Undefined label 'block_1'
  })();
}

Specifications

Browser compatibility

See also

• continue
• label
• switch