Web/JavaScript/Reference/Global objects/WeakSet/add

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

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Syntax

ws.add(value);

Parameters

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

Return value

The WeakSet object.

Examples

Using add

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

ECMAScript (ECMA-262)The definition of 'WeakSet.prototype.add' 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
`add`	Chrome Full support 36	Edge Full support 12	Firefox Full support 34	IE No support No	Opera Full support 23	Safari Full support 9	WebView Android Full support 37	Chrome Android Full support 36	Firefox Android Full support 34	Opera Android Full support 24	Safari iOS Full support 9	Samsung Internet Android Full support 3.0	nodejs Full support 0.12

Legend

Full support: Full support
No support: No support