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WeakSet.prototype.add()

The add() method appends a new object to the end of a WeakSet object.

Syntax

ws.add(value);

Parameters

value
Required. The object to add to the WeakSet collection.

Return value

The WeakSet object.

Using the add method

var ws = new WeakSet();

ws.add(window); // add the window object to the WeakSet

ws.has(window); // true

// Weakset only takes objects as arguments
ws.add(1);
// results in "TypeError: Invalid value used in weak set" in Chrome
// and "TypeError: 1 is not a non-null object" in Firefox

Specifications

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

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support 36 34 (34) No support 23 No support
Feature Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support No support 34.0 (34) No support No support No support

See also

Document Tags and Contributors

 Contributors to this page: eduardoboucas, chrisdavidmills, andradei, fscholz, realityking, teoli
 Last updated by: eduardoboucas,