TypedArray and ArrayBuffer support for @@species

test/mjsunit/es6/legacy-subclassing.js

+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Before Symbol.species was added, ArrayBuffer subclasses constructed

[adamk, 2016/01/12 00:11:00]

Might as well add:

// Flags: --noharmony-species

to this? That way you won't have to add it later.

+// ArrayBuffers, but TypedArray and Promise subclasses constructed an instance
+// of the subclass.
+
+'use strict';
+
+assertEquals(undefined, Symbol.species);
+
+class MyUint8Array extends Uint8Array { }
+Object.defineProperty(MyUint8Array.prototype, "BYTES_PER_ELEMENT", {value: 1});
+let myArray = new MyUint8Array(3);
+assertEquals(MyUint8Array, myArray.constructor);
+assertEquals(MyUint8Array, myArray.map(x => x + 1).constructor);
+
+class MyArrayBuffer extends ArrayBuffer { }
+let myBuffer = new MyArrayBuffer(0);
+assertEquals(MyArrayBuffer, myBuffer.constructor);
+assertEquals(ArrayBuffer, myBuffer.slice().constructor);
+
+class MyPromise extends Promise { }
+let myPromise = new MyPromise(() => {});
+assertEquals(MyPromise, myPromise.constructor);
+assertEquals(MyPromise, myPromise.then().constructor);