for-in-order.js - mozsearch

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/* Any copyright is dedicated to the Public Domain.

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

// ES6 does not specify enumeration order, but implementations mostly retain

// property insertion order -- and must, for web compatibility. This test checks

// that symbol-keyed properties do not interfere with that order.

var obj = {};

obj[Symbol("moon")] = 0;

obj.x = 1;

obj[Symbol.for("y")] = 2

obj.y = 3;

obj[Symbol.iterator] = function* () { yield 4; };

obj.z = 5;

Object.prototype[Symbol.for("comet")] = 6;

var keys = [];

for (var k in obj)

    keys.push(k);

assertDeepEq(keys, ["x", "y", "z"]);

assertDeepEq(Object.keys(obj), ["x", "y", "z"]);

// Test with more properties.

for (var i = 0; i < 1000; i++)

    obj[Symbol(i)] = i;

obj.w = 1000;

keys = []

for (var k in obj)

    keys.push(k);

assertDeepEq(keys, ["x", "y", "z", "w"]);

if (typeof reportCompare === "function")

    reportCompare(0, 0);