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
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) { var i = 0; while (i < 6) { if (i == 3) { break; } i += 1; } return i * x; }
break in labeled blocks
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 }
break in labeled blocks that throw
The following code also uses break
statements with labeled blocks, but generates a SyntaxError
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'); }
break within functions
SyntaxError
s 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
Specification |
---|
ECMAScript (ECMA-262) The definition of 'Break statement' in that specification. |
Browser compatibility
Desktop | Mobile | Server | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
break | Chrome Full support 1 | Edge Full support 12 | Firefox Full support 1 | IE Full support 3 | Opera Full support 4 | Safari Full support 1 | WebView Android Full support 1 | Chrome Android Full support 18 | Firefox Android Full support 4 | Opera Android Full support 10.1 | Safari iOS Full support 1 | Samsung Internet Android Full support 1.0 | nodejs Full support 0.1.100 |
Legend
- Full support
- Full support