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// Copyright (C) 2019 Leo Balter. All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.
/*---
esid: sec-proxy-object-internal-methods-and-internal-slots-getprototypeof
description: >
instanceof operator observes the TypeError from a custom trap result that would return true if
the target were extensible.
info: |
Runtime Semantics: InstanceofOperator ( V, target )
5. Return ? OrdinaryHasInstance(target, V).
OrdinaryHasInstance ( C, O )
4. Let P be ? Get(C, "prototype").
...
6. Repeat,
a. Set O to ? O.[[GetPrototypeOf]]().
b. If O is null, return false.
c. If SameValue(P, O) is true, return true.
[[GetPrototypeOf]] ( )
7. Let handlerProto be ? Call(trap, handler, « target »).
8. If Type(handlerProto) is neither Object nor Null, throw a TypeError exception.
9. Let extensibleTarget be ? IsExtensible(target).
10. If extensibleTarget is true, return handlerProto.
11. Let targetProto be ? target.[[GetPrototypeOf]]().
12. If SameValue(handlerProto, targetProto) is false, throw a TypeError exception.
features: [Proxy]
---*/
function Custom() {}
var target = {};
var p = new Proxy(target, {
getPrototypeOf() {
return Custom.prototype;
}
});
Object.preventExtensions(target);
assert.throws(TypeError, () => {
p instanceof Custom
});
reportCompare(0, 0);
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