Fastest array loops in Javascript (v479)

Revision 479 of this benchmark created by Scott Jackson on

Preparation HTML

<script>
  // Populate the base array
  var arr = [];
  for (var i = 0; i < 1000; i++) {
    arr[i] = i;
  }
var len= arr.length;
  function someFn(ix) {
    return ix * 5 + 1 / 3 * 8;
  }
</script>

Test runner

Ready to run.

Testing in
TestOps/sec
While length--
var l = arr.length;
while(l--) {
  someFn(arr[l]);
}
ready
While loop, basic
var i = 0;
while (i < arr.length) {
  someFn(arr[i]);
  i++;
}
ready
For loop, cached
for (var i = 0, len = arr.length; i < len; i++) {
  someFn(arr[i]);
}
ready
Order
while( i = arr.shift() ) {
  someFn(i);
}
ready
order validation
while( (i = arr.shift()) !== undefined ) {
  someFn(i);
}
ready
For loop, basic
for (var i = 0; i < arr.length; i++) {
  someFn(arr[i]);
}
ready
For loop, adv
var i = 0
for (; i < arr[i]; i++) {
  someFn(arr[i]);
}
ready
for (var i = 0; i < len; i++) {
  someFn(arr[i]);
}
ready
Reverse Iteration
for (var l = arr.length-1; l >=0 ; l--) {
  someFn(arr[l]);
}
ready

Revisions

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