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The add() method appends a new element with a specified value to the end of a Set object.




Required. The value of the element to add to the Set object.

Return value

The Set object.


Using the add method

var mySet = new Set();

mySet.add(5).add("some text"); // chainable

// Set [1, 5, "some text"]


Specification Status Comment
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Set.prototype.add' in that specification.
Standard Initial definition.
ECMAScript 2017 Draft (ECMA-262)
The definition of 'Set.prototype.add' in that specification.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support 38 13.0 (13.0) 11 25 7.1
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support No support 38 13.0 (13.0) No support No support 8

Firefox-specific notes

  • Prior to Firefox 33 (Firefox 33 / Thunderbird 33 / SeaMonkey 2.30), Set.prototype.add returned undefined and was not chainable. This has been fixed (bug 1031632). The behavior can be found in Chrome/v8 as well (issue).

See also

Document Tags and Contributors

 Contributors to this page: SphinxKnight, kyliau, Davidpsjunior, fscholz, realityking, ziyunfei
 Last updated by: SphinxKnight,