The has() method returns a boolean indicating whether an element with the specified value exists in a Set object or not.




The value to test for presence in the Set object.

Return value

Returns true if an element with the specified value exists in the Set object; otherwise false.

Note: Technically speaking, has() uses the sameValueZero algorithm to determine whether the given element is found.


Using the has method

var mySet = new Set();

mySet.has('foo');  // returns true
mySet.has('bar');  // returns false

var set1 = new Set();
var obj1 = {'key1': 1};

set1.has(obj1);        // returns true
set1.has({'key1': 1}); // returns false because they are different object references
set1.add({'key1': 1}); // now set1 contains 2 entries


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

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
hasChrome Full support 38Edge Full support 12Firefox Full support 13IE Full support 11Opera Full support 25Safari Full support 8WebView Android Full support 38Chrome Android Full support 38Firefox Android Full support 14Opera Android Full support 25Safari iOS Full support 8Samsung Internet Android Full support Yesnodejs Full support Yes


Full support  
Full support

See also

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