# Packed vs. holey arrays

## JavaScript performance comparison

Revision 4 of this test case created by Yu-Cheng Chuang

## Preparation code

`` <script>  Benchmark.prototype.setup = function() {    var packed_array = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];        var holey_array1 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];    delete holey_array1[0];        var holey_array2 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];    holey_array2[13] = 0;        var holey_array3 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, /* hole */, 10];        var holey_array4 = new Array(10);        // only fill the first 9 elements    for (var i  = 0; i < 9; i++) {      holey_array4[i] = i;    }        function packed_sum() {      var sum = 0;      for (var i = 0; i < packed_array.length; i++) {        sum += packed_array[i];      }    }        function holey_sum1() {      var sum = 0;      for (var i = 0; i < holey_array1.length; i++) {        sum += holey_array1[i];      }    }        function holey_sum2() {      var sum = 0;      for (var i = 0; i < holey_array2.length; i++) {        sum += holey_array2[i];      }    }        function holey_sum3() {      var sum = 0;      for (var i = 0; i < holey_array3.length; i++) {        sum += holey_array3[i];      }    }            function holey_sum4() {      var sum = 0;      for (var i = 0; i < holey_array4.length; i++) {        sum += holey_array4[i];      }    }  };</script>``

## Test runner

Warning! For accurate results, please disable Firebug before running the tests. (Why?)

Java applet disabled.

Testing in unknown unknown
Test Ops/sec
Packed array sum
``packed_sum();``
pending…
Holey array sum 1
``holey_sum1();``
pending…
Holey array sum 2
``holey_sum2();``
pending…
Holey array sum 3
``holey_sum3();``
pending…
Holey array sum 4
``holey_sum4();``
pending…

## Revisions

You can edit these tests or add even more tests to this page by appending `/edit` to the URL. Here’s a list of current revisions for this page: