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/* Any copyright is dedicated to the Public Domain.
* http://creativecommons.org/licenses/publicdomain/ */
// Two tests involving Array.from and a Proxy.
var log = [];
function LoggingProxy(target) {
var h = {
defineProperty: function (t, id) {
log.push("define", id);
return true;
},
has: function (t, id) {
log.push("has", id);
return id in t;
},
get: function (t, id) {
log.push("get", id);
return t[id];
},
set: function (t, id, v) {
log.push("set", id);
t[id] = v;
return true;
}
};
return new Proxy(target || [], h);
}
// When the new object created by Array.from is a Proxy,
// Array.from calls handler.defineProperty to create new elements
// but handler.set to set the length.
LoggingProxy.from = Array.from;
LoggingProxy.from([3, 4, 5]);
assertDeepEq(log, ["define", "0", "define", "1", "define", "2", "set", "length"]);
// When the argument passed to Array.from is a Proxy, Array.from
// calls handler.get on it.
log = [];
assertDeepEq(Array.from(new LoggingProxy([3, 4, 5])), [3, 4, 5]);
assertDeepEq(log, ["get", Symbol.iterator,
"get", "length", "get", "0",
"get", "length", "get", "1",
"get", "length", "get", "2",
"get", "length"]);
// Array-like iteration only gets the length once.
log = [];
var arr = [5, 6, 7];
arr[Symbol.iterator] = undefined;
assertDeepEq(Array.from(new LoggingProxy(arr)), [5, 6, 7]);
assertDeepEq(log, ["get", Symbol.iterator,
"get", "length", "get", "0", "get", "1", "get", "2"]);
if (typeof reportCompare === 'function')
reportCompare(0, 0);
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