Info

I know that reverse while looping in javascript is faster than for looping, but if order is to be maintained, would rev-while looping then reversing the array be faster or would the traditional for loop out perform this combo?

See http://jsperf.com/js-array-reverse-vs-while-loop/5.

See http://jsperf.com/array-push-reverse-vs-unshift-reverse for array push reverse vs. unshift reverse.

See http://jsperf.com/array-push-vs-unshift/6 for array push vs. unshift reversal.

Preparation code

 
<script>
  Benchmark.prototype.setup = function() {
    var array = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
    var length = array.length;
  };
</script>

Test runner

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var start = null;
var end = null;
for (start = 0; start < length / 2; start += 1) {
  var temporary = array[start];
  end = length - 1 - start;
  array[start] = array[end];
  array[end] = temporary;
}

var end = null;
var start = null;
for (end = length - 1; end >= length / 2; end -= 1) {
  var temporary = array[end];
  start = length - 1 - end;
  array[end] = array[start];
  array[start] = temporary;
}

var start = 0;
var end = null;
while (start < length / 2) {
  var temporary = array[start];
  end = length - 1 - start;
  array[start] = array[end];
  array[end] = temporary;
  start += 1;
}

var end = length - 1;
var start = null;
while (end >= length / 2) {
  var temporary = array[end];
  start = length - 1 - end;
  array[end] = array[start];
  array[start] = temporary;
  end -= 1;
}

array.reverse();

var temporary = [];
var i = null;
for (i = 0; i < length; i += 1) {
  temporary.push(array[i]);
}
array = temporary;

var temporary = [];
var i = null;
for (i = 0; i < length; i += 1) {
  temporary.unshift(array[i]);
}
array = temporary;

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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 by Dan Masquelier on 22nd August 2011
• Revision 2: published on 25th August 2011
• Revision 3: published on 25th August 2011
• Revision 4: published on 9th September 2011
• Revision 5: published on 8th December 2011
• Revision 6: published on 8th December 2011
• Revision 7: published on 8th December 2011
• Revision 8: published by vamp on 9th December 2011
• Revision 9: published by XP1 on 2nd February 2012
• Revision 10: published by XP1 on 2nd February 2012

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