break
The break statement terminates the current loop, switch
, or label
statement and transfers program control to the statement following the terminated statement.
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.
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'); }
Specifications
Specification | Status | Comment |
---|---|---|
ECMAScript 1st Edition (ECMA-262) | Standard | Initial definition. Unlabeled version. |
ECMAScript 3rd Edition (ECMA-262) | Standard | Labeled version added. |
ECMAScript 5.1 (ECMA-262) The definition of 'Break statement' in that specification. |
Standard | |
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Break statement' in that specification. |
Standard | |
ECMAScript 2017 Draft (ECMA-262) The definition of 'Break statement' in that specification. |
Draft |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) |
See also
License
© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-us/docs/web/javascript/reference/statements/break