18 lines
619 B
JavaScript
18 lines
619 B
JavaScript
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// Copyright 2018 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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const arr = [1, , 3];
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function mapper(x) {
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Array.prototype[1] = 2;
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return x + 1;
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}
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// We force a direct iteration (using the array length, not the iterator
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// protocol). The mapper function gets called during this iteration, not in a
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// separate one. Hence when index 1 is read, 2 is retrieved from the prototype
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// and incremented to 3.
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Array.prototype[Symbol.iterator] = undefined;
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assertArrayEquals([2, 3, 4], Uint16Array.from(arr, mapper));
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