| // Copyright (C) 2016 the V8 project authors. All rights reserved. |
| // This code is governed by the BSD license found in the LICENSE file. |
| /*--- |
| es6id: 23.3.1 |
| description: Subclassing the WeakMap object |
| info: | |
| 23.3.1 The WeakMap Constructor |
| |
| ... |
| |
| The WeakMap constructor is designed to be subclassable. It may be used as the |
| value in an extends clause of a class definition. Subclass constructors that |
| intend to inherit the specified WeakMap behaviour must include a super call to |
| the WeakMap constructor to create and initialize the subclass instance with |
| the internal state necessary to support the WeakMap.prototype built-in |
| methods. |
| ---*/ |
| |
| class WM extends WeakMap {} |
| |
| var map = new WM(); |
| var obj = {}; |
| |
| assert.sameValue(map.has(obj), false); |
| |
| map.set(obj, 42); |
| assert.sameValue(map.has(obj), true); |
| assert.sameValue(map.get(obj), 42); |
