Web/JavaScript/Reference/Global objects/Set/has

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

Syntax

mySet.has(value);

Parameters

value: 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 Same-value-zero algorithm to determine whether the given element is found.

Examples

Using the has() method

var mySet = new Set();
mySet.add('foo');

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

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

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

Specifications

Specification
ECMAScript (ECMA-262)The definition of 'Set.prototype.has' in that specification.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
`has`	Chrome Full support 38	Edge Full support 12	Firefox Full support 13	IE Full support 11	Opera Full support 25	Safari Full support 8	WebView Android Full support 38	Chrome Android Full support 38	Firefox Android Full support 14	Opera Android Full support 25	Safari iOS Full support 8	Samsung Internet Android Full support 3.0	nodejs Full support 0.12 Full support 0.12 Full support 0.10 Disabled' Disabled' From version 0.10: this feature is behind the `--harmony` runtime flag.

Legend

Full support: Full support
User must explicitly enable this feature.': User must explicitly enable this feature.