Set.prototype.has()

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

Syntax

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 Language Specification
# sec-set.prototype.has

Browser compatibility

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See also