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/* Any copyright is dedicated to the Public Domain.
* http://creativecommons.org/licenses/publicdomain/ */
// Array.from works on arguments objects.
(function () {
assertDeepEq(Array.from(arguments), ["arg0", "arg1", undefined]);
})("arg0", "arg1", undefined);
// If an object has both .length and [@@iterator] properties, [@@iterator] is used.
var a = ['a', 'e', 'i', 'o', 'u'];
a[Symbol.iterator] = function* () {
for (var i = 5; i--; )
yield this[i];
};
var log = '';
function f(x) {
log += x;
return x + x;
}
var b = Array.from(a, f);
assertDeepEq(b, ['uu', 'oo', 'ii', 'ee', 'aa']);
assertEq(log, 'uoiea');
// In fact, if [@@iterator] is present, .length isn't queried at all.
var pa = new Proxy(a, {
has: function (target, id) {
if (id === "length")
throw new Error(".length should not be queried (has)");
return id in target;
},
get: function (target, id) {
if (id === "length")
throw new Error(".length should not be queried (get)");
return target[id];
},
getOwnPropertyDescriptor: function (target, id) {
if (id === "length")
throw new Error(".length should not be queried (getOwnPropertyDescriptor)");
return Object.getOwnPropertyDescriptor(target, id)
}
});
log = "";
b = Array.from(pa, f);
assertDeepEq(b, ['uu', 'oo', 'ii', 'ee', 'aa']);
assertEq(log, 'uoiea');
if (typeof reportCompare === 'function')
reportCompare(0, 0);
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