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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.
/*---
esid: sec-isconcatspreadable
description: >
Proxies who final targets are arrays are considered spreadable
info: |
[...]
5. Repeat, while items is not empty
a. Remove the first element from items and let E be the value of the
element.
b. Let spreadable be ? IsConcatSpreadable(E).
c. If spreadable is true, then
[...]
e. Else E is added as a single item rather than spread,
[...]
ES6 22.1.3.1.1: Runtime Semantics: IsConcatSpreadable ( O )
1. If Type(O) is not Object, return false.
2. Let spreadable be ? Get(O, @@isConcatSpreadable).
3. If spreadable is not undefined, return ToBoolean(spreadable).
4. Return ? IsArray(O).
7.2.2 IsArray
[...]
3. If argument is a Proxy exotic object, then
a. If the value of the [[ProxyHandler]] internal slot of argument is null,
throw a TypeError exception.
b. Let target be the value of the [[ProxyTarget]] internal slot of
argument.
c. Return ? IsArray(target).
features: [Proxy, Symbol.isConcatSpreadable]
---*/
var arrayProxy = new Proxy([], {});
var arrayProxyProxy = new Proxy(arrayProxy, {});
var spreadable = {};
spreadable[Symbol.isConcatSpreadable] = true;
var spreadableProxy = new Proxy(spreadable, {});
assert.sameValue([].concat(arrayProxy).length, 0, 'The value of [].concat(arrayProxy).length is expected to be 0');
assert.sameValue(
[].concat(arrayProxyProxy).length, 0, 'The value of [].concat(arrayProxyProxy).length is expected to be 0'
);
assert.sameValue(
[].concat(spreadableProxy).length,
0,
'The value of [].concat(spreadableProxy).length is expected to be 0'
);
reportCompare(0, 0);
|
