property-basics.js

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/* Any copyright is dedicated to the Public Domain.

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

var symbols = [

    Symbol(),

    Symbol("one"),

    Symbol.for("two"),

    Symbol.iterator,

    Object(Symbol())

];

for (var sym of symbols) {

    var obj = {};

    // access a nonexistent property

    assertEq(sym in obj, false);

    assertEq(obj.hasOwnProperty(sym), false);

    assertEq(obj[sym], undefined);

    assertEq(typeof obj[sym], "undefined");

    assertEq(Object.getOwnPropertyDescriptor(obj, sym), undefined);

    // assign, then try accessing again

    obj[sym] = "ok";

    assertEq(sym in obj, true);

    assertEq(obj.hasOwnProperty(sym), true);

    assertEq(obj[sym], "ok");

    assertDeepEq(Object.getOwnPropertyDescriptor(obj, sym), {

        value: "ok",

        writable: true,

        enumerable: true,

        configurable: true

});

    // assign again, observe value is overwritten

    obj[sym] = 12;

    assertEq(obj[sym], 12);

    // increment

    assertEq(obj[sym]++, 12);

    assertEq(obj[sym], 13);

if (typeof reportCompare === "function")

    reportCompare(0, 0);