 <p>Just like Perl,</p> <pre><code>loop1: for (var i in set1) { loop2: for (var j in set2) { loop3: for (var k in set3) { break loop2; // breaks out of loop3 and loop2 } } } </code></pre> <p>as defined in EMCA-262 section 12.12. <a href="https://developer.mozilla.org/en/JavaScript/Reference/Statements/label" rel="nofollow noreferrer">[MDN Docs]</a></p> <p>Unlike C, these labels can only be used for <a href="https://developer.mozilla.org/en/JavaScript/Reference/Statements/continue" rel="nofollow noreferrer"><code>continue</code></a> and <a href="https://developer.mozilla.org/en/JavaScript/Reference/Statements/break" rel="nofollow noreferrer"><code>break</code></a>, as Javascript does not have <code>goto</code> (without hacks like <a href="http://www.summerofgoto.com/" rel="nofollow noreferrer">this</a>).</p>