array-length-protochange.js

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// Any copyright is dedicated to the Public Domain.

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

//-----------------------------------------------------------------------------

var BUGNUMBER = 548671;

var summary =

  "Don't use a shared-permanent inherited property to implement " +

  "[].length or (function(){}).length";

print(BUGNUMBER + ": " + summary);

/**************

 * BEGIN TEST *

 **************/

var a = [1, 2, 3];

a.__proto__ = null;

reportCompare("length" in a, true, "length should be own property of array");

reportCompare(Object.hasOwnProperty.call(a, "length"), true,

              "length should be own property of array");

reportCompare(a.length, 3, "array length should be 3");

var a = [], b = [];

b.__proto__ = a;

reportCompare(b.hasOwnProperty("length"), true,

              "length should be own property of array");

b.length = 42;

reportCompare(b.length, 42, "should have mutated b's (own) length");

reportCompare(a.length, 0, "should not have mutated a's (own) length");

if (typeof reportCompare === "function")

  reportCompare(true, true);

print("All tests passed!");