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27 lines
747 B
JavaScript
27 lines
747 B
JavaScript
// Copyright (c) 2020 Ecma International. All rights reserved.
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// This code is governed by the BSD license found in the LICENSE file.
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/*---
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esid: sec-assignment-operators-runtime-semantics-evaluation
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description: >
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Strict Mode - TypeError is thrown if the LeftHandSide of a Logical
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Assignment operator(??=) is a reference to a data property with the
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attribute value {[[Writable]]:false} and PutValue step is reached.
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flags: [onlyStrict]
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features: [logical-assignment-operators]
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---*/
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var obj = {};
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Object.defineProperty(obj, "prop", {
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value: undefined,
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writable: false,
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enumerable: true,
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configurable: true
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});
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assert.throws(TypeError, function() {
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obj.prop ??= 1;
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});
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assert.sameValue(obj.prop, undefined, "obj.prop");
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