The get() method returns a specified element from a WeakMap object.
The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.
Syntax
wm.get(key);Parameters
- key
- Required. The key of the element to return from the
WeakMapobject.
Return value
The element associated with the specified key in the WeakMap object. If the key can't be found, undefined is returned.
Examples
Using the get method
var wm = new WeakMap();
wm.set(window, 'foo');
wm.get(window); // Returns "foo".
wm.get('baz'); // Returns undefined.
Specifications
| Specification | Status | Comment |
|---|---|---|
| ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'WeakMap.prototype.get' in that specification. |
Standard | Initial definition. |
| ECMAScript Latest Draft (ECMA-262) The definition of 'WeakMap.prototype.get' in that specification. |
Draft |
Browser compatibility
| Feature | Chrome | Edge | Firefox | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|---|
| Basic support | 36 | Yes | 61 | 11 | 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. However, the ES2015 specification specifies to return undefined instead. Furthermore, WeakMap.prototype.get accepted an optional second argument as a fallback value, which is not part of the standard. Both non-standard behaviors are removed in version 38 and higher.
2. From version 0.10: this feature is behind the --harmony runtime flag.