JS: Array.reverse() vs. for and while loops (v57)

Revision 57 of this benchmark created by jeko on

Description

Checking performance of Array.reverse() vs custom loops.

See http://stackoverflow.com/questions/5276953/what-is-the-most-efficient-way-to-reverse-an-array-in-javascript.

Also see http://jsperf.com/forloop-vs-reverse-while-loop-and-array-reverse/9.

Preparation HTML

<script>
    var array = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
    var length = array.length;
</script>

Test runner

Ready to run.

Testing in
TestOps/sec
Array.reverse()
array.reverse();
ready
while push then slice
var left = 0;
while (left < length) {
  array.push(array[length - 1 - ++left]);
  array.splice(length - 1 - left, 1);
}
ready
while forward
var left = 0;
while (left < length) {
  var right = length - 1 - left;
  array.push(array[right]);
  array.splice(right, 1);
  left += 1;
}
ready
for push then slice
for (length -= 2; length > -1; length -= 1) {
  array.push(array[length]);
  array.splice(length, 1);
}
ready
for push
var result = [];
var i = null;
for (i = length - 1; i >= 0; i -= 1) {
  result.push(array[i]);
}
ready
for swap
var left = null;
var right = null;
for (left = 0, right = length - 1; left < right; left += 1, right -= 1) {
  var temporary = array[left];
  array[left] = array[right];
  array[right] = temporary;
}
ready
for swap half
var left = null;
var right = null;
for (left = 0; left < length / 2; left += 1) {
  right = length - 1 - left;
  var temporary = array[left];
  array[left] = array[right];
  array[right] = temporary;
}
ready
XOR swap
var i = null;
var r = null;
for (i = 0, r = length - 1; i < r; i += 1, r -= 1) {
  var left = array[i];
  var right = array[r];
  left ^= right;
  right ^= left;
  left ^= right;
  array[i] = left;
  array[r] = right;
}
ready
XOR swap half
var i = null;
var r = null;
for (i = 0; i < length / 2; i += 1) {
  r = length - 1 - i;
  var left = array[i];
  var right = array[r];
  left ^= right;
  right ^= left;
  left ^= right;
  array[i] = left;
  array[r] = right;
}
ready
destructuring
var left = null;
var right = null;
for (left = 0, right = length - 1; left < right; left += 1, right -= 1) {
  [array[left], array[right]] = [array[right], array[left]];
}
ready
destructuring half
var left = null;
var right = null;
for (left = 0; left < length / 2; left += 1) {
  right = length - 1 - left;
  [array[left], array[right]] = [array[right], array[left]];
}
ready
No array methods
for (var i = length; i > 0; --i) {
  newArr[newArr.length] = arr[i - 1];
}
ready

Revisions

You can edit these tests or add more tests to this page by appending /edit to the URL.