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 Latest Draft (ECMA-262)
The definition of 'WeakSet.prototype.add' in that specification.
Draft  

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support36 Yes34 No239
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support3636 Yes34239 ?

See also

Document Tags and Contributors

 Last updated by: wbamberg,