regular-subclassing.js (805B)
1 // Copyright (C) 2016 the V8 project authors. All rights reserved. 2 // This code is governed by the BSD license found in the LICENSE file. 3 /*--- 4 es6id: 23.1.1 5 description: Subclassing the Map object 6 info: | 7 23.1.1 The Map Constructor 8 9 ... 10 11 The Map constructor is designed to be subclassable. It may be used as the 12 value in an extends clause of a class definition. Subclass constructors that 13 intend to inherit the specified Map behaviour must include a super call to the 14 Map constructor to create and initialize the subclass instance with the 15 internal state necessary to support the Map.prototype built-in methods. 16 ---*/ 17 18 class M extends Map {} 19 20 var map = new M([{ 'foo': 'bar' }]); 21 22 assert.sameValue(map.size, 1); 23 24 map.set('bar', 'baz'); 25 26 assert.sameValue(map.size, 2); 27 28 reportCompare(0, 0);