regular-subclassing.js

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// Copyright (C) 2016 the V8 project authors. All rights reserved.

// This code is governed by the BSD license found in the LICENSE file.

/*---

es6id: 22.1.1

description: Subclassing Array

info: |

  22.1.1 The Array Constructor

  The Array constructor is designed to be subclassable. It may be used as the

  value of an extends clause of a class definition. (...)

includes: [compareArray.js]

---*/

class Sub extends Array {}

var a1 = new Sub(42, 'foo');

assert.sameValue(a1.length, 2);

assert.sameValue(a1[0], 42);

assert.sameValue(a1[1], 'foo');

a1.push(true);

assert.sameValue(a1.length, 3, 'Array#push updates the length property');

assert.sameValue(a1[0], 42);

assert.sameValue(a1[1], 'foo');

assert.sameValue(a1[2], true, 'Adds new item');

var a2 = new Sub(7);

assert.sameValue(a2.length, 7);

var a3 = new Sub();

assert.compareArray(a3, []);

assert.sameValue(a3.length, 0);

reportCompare(0, 0);