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. The key of the element to add to the
WeakMapobject. - value
- Required. The value of the element to add to the
WeakMapobject.
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 | Status | Comment |
|---|---|---|
| ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'WeakMap.prototype.set' in that specification. |
Standard | Initial definition. |
| ECMAScript Latest Draft (ECMA-262) The definition of 'WeakMap.prototype.set' in that specification. |
Draft |
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.
| Feature | Chrome | Edge | Firefox | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|---|
| Basic support | 36 | Yes | 61 | 112 | 23 | 8 |
| Feature | Android webview | Chrome for Android | Edge mobile | Firefox for Android | Opera Android | iOS Safari | Samsung Internet |
|---|---|---|---|---|---|---|---|
| Basic support | 36 | 36 | Yes | 61 | 23 | 8 | Yes |
1. 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.
2. Returns 'undefined' instead of the 'Map' object.
3. From version 0.10: this feature is behind the --harmony runtime flag.
Firefox-specific notes
- Prior to Firefox 33 (Firefox 33 / Thunderbird 33 / SeaMonkey 2.30),
WeakMap.prototype.setreturnedundefinedand was not chainable. This has been fixed (bug 1031632). The behavior can be found in Chrome/v8 as well (issue).