Fastest array loops in Javascript (v104)

Revision 104 of this benchmark created by Fabio Costa on

Preparation HTML

<script>
  function someFn(ix) {
    return ix * 5 + 1 / 3 * 8;
  }
</script>

Setup

// Populate the base array
    var arr = [];
    for (var i = 0; i < 1000; i++) {
      arr[i] = i;
    }

Test runner

Ready to run.

Testing in
TestOps/sec
For loop, basic
for (var i = 0; i < arr.length; i++) {
  someFn.call(arr, arr[i]);
}
ready
While loop, basic
var i = 0;
while (i < arr.length) {
  someFn.call(arr, arr[i]);
  i++;
}
ready
For loop, cached
for (var i = 0, len = arr.length; i < len; i++) {
  someFn.call(arr, arr[i]);
}
ready
For loop, i--
for (var i = arr.length; i > 0; i--) {
  someFn.call(arr, arr[i]);
}
ready
Do-while loop, i--
var i = arr.length - 1;
do {
  someFn.call(arr, arr[i]);
}
while (i--);
ready
Do-while loop, --i
var i = arr.length;
if (i > 0) {
  do {
    someFn.call(arr, arr[i]);
  }
  while (--i);
}
ready
For..in loop
for (var i in arr) {
  someFn.call(arr, arr[i]);
}
ready
forEach
arr.forEach(someFn);
ready
While ! Undefined
var a, i = 0;
while((a = arr[i++]) !== undefined) {
  someFn.call(arr, a);
}
ready
While length--
var l = arr.length;
while(l--) {
  someFn.call(arr, arr[l]);
}
ready

Revisions

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