enumeration.js - mozsearch

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/* Any copyright is dedicated to the Public Domain.

 * http://creativecommons.org/licenses/publicdomain/ */

// for-in loops skip properties with symbol keys, even enumerable properties.

var obj = {};

obj[Symbol.for("moon")] = "sun";

obj[Symbol("asleep")] = "awake";

obj[Symbol.iterator] = "List";

for (var x in obj)

    throw "FAIL: " + String(x);

// This includes inherited properties.

var obj2 = Object.create(obj);

for (var x in obj2)

    throw "FAIL: " + String(x);

// The same goes for proxies.

var p = new Proxy(obj, {});

for (var x in p)

    throw "FAIL: " + String(x);

var p2 = new Proxy(obj2, {});

for (var x in p2)

    throw "FAIL: " + String(x);

// Object.keys() and .getOwnPropertyNames() also skip symbols.

assertEq(Object.keys(obj).length, 0);

assertEq(Object.keys(p).length, 0);

assertEq(Object.keys(obj2).length, 0);

assertEq(Object.keys(p2).length, 0);

assertEq(Object.getOwnPropertyNames(obj).length, 0);

assertEq(Object.getOwnPropertyNames(p).length, 0);

assertEq(Object.getOwnPropertyNames(obj2).length, 0);

assertEq(Object.getOwnPropertyNames(p2).length, 0);

// Test interaction of Object.keys(), proxies, and symbol property keys.

var log = [];

var h = {

    ownKeys: (t) => {

        log.push("ownKeys");

        return ["a", "0", Symbol.for("moon"), Symbol("asleep"), Symbol.iterator];

},

    getOwnPropertyDescriptor: (t, key) => {

        log.push("gopd", key);

        return {configurable: true, enumerable: true, value: 0, writable: true};

};

p = new Proxy({}, h);

assertDeepEq(Object.keys(p), ["a", "0"]);

assertDeepEq(log, ["ownKeys", "gopd", "a", "gopd", "0"]);

if (typeof reportCompare === "function")

    reportCompare(0, 0);