Loop iteration (length comparison variations)

JavaScript performance comparison

Revision 2 of this test case created on 7th August 2011
Info

Comparison of different ways to treat the length of an array when iterating the array.
Preparation code

<script>
  var list = [
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries",
      "oranges",
      "apples",
      "tangerines",
      "watermelon",
      "nectarines",
      "peaches",
      "strawberries"
  ];
</script>
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Testing in unknown unknown
Test		Ops/sec
Using list.length	`for (var i = 0; i < list.length; i++) { var fruit = list[i]; }`	pending…
Using static len	`for (var i = 0, len = list.length; i < len; i++) { var fruit = list[i]; }`	pending…
Reverse Loop (for)	`for (var i = list.length; i--; ) { var fruit = list[i]; }`	pending…
Reverse Loop (while)	`var i = list.length; while (i--) { var fruit = list[i]; }`	pending…
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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:
Revision 1: published on 7th August 2011
Revision 2: published on 7th August 2011
Revision 3: published on 9th May 2012
Revision 4: published on 26th July 2012
Revision 5: published on 26th July 2012
Revision 6: published by Vance Ingalls on 27th September 2012
Revision 7: published on 27th September 2012
Revision 8: published by Vance Ingalls on 27th September 2012
Revision 9: published by Raymond on 30th January 2013
Revision 10: published on 6th February 2013
Revision 11: published on 8th May 2013
Revision 12: published on 8th May 2013