Web/JavaScript/Reference/Global objects/WeakMap/set

The set() method adds a new element with a specified key and value to a WeakMap object.

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Syntax

wm.set(key, value);

Parameters

key

Required. Must be object. The key of the element to add to the WeakMap object.

value

Required. Any value. The value of the element to add to the WeakMap object.

Return value

The WeakMap object.

Examples

Using the set() method

var wm = new WeakMap();
var obj = {};

// Add new elements to the WeakMap
wm.set(obj, 'foo').set(window, 'bar'); // chainable

// Update an element in the WeakMap
wm.set(obj, 'baz');

Specifications

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

Browser compatibility

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

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
set	Chrome Full support 36	Edge Full support 12	Firefox Full support 6 Notes' Full support 6 Notes' Notes' Prior to Firefox 38, this method threw a TypeError when the key parameter was not an object. This has been fixed in version 38 and later to return false as per the ES2015 standard.	IE Partial support 11 Notes' Partial support 11 Notes' Notes' Returns 'undefined' instead of the 'Map' object.	Opera Full support 23	Safari Full support 8	WebView Android Full support 37	Chrome Android Full support 36	Firefox Android Full support 6 Notes' Full support 6 Notes' Notes' Prior to Firefox 38, this method threw a TypeError when the key parameter was not an object. This has been fixed in version 38 and later to return false as per the ES2015 standard.	Opera Android Full support 24	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

Partial support  

Partial support

See implementation notes.'

See implementation notes.

User must explicitly enable this feature.'

User must explicitly enable this feature.

See also

• WeakMap
• WeakMap.prototype.get()
• WeakMap.prototype.has()

WeakMap.prototype.set() by Mozilla Contributors is licensed under CC-BY-SA 2.5.