Fastest array loops in Javascript

JavaScript performance comparison

Revision 408 of this test case created by Roman

Preparation code

<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 Math.random();
  }
</script>
    

Test runner

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Testing in CCBot 2.0.0 / Other 0.0.0
Test Ops/sec
While length--
var l = arr.length;
while(l--) {
  someFn(arr[l]);
}
pending…
While loop, basic
var i = 0;
while (i < arr.length) {
  someFn(arr[i]);
  i++;
}
pending…
For loop, cached
for (var i = 0, len = arr.length; i < len; i++) {
  someFn(arr[i]);
}
pending…
For loop, basic
for (var i = 0; i < arr.length; i++) {
  someFn(arr[i]);
}
pending…
For loop, adv
var i = 0
for (; i < arr[i]; i++) {
  someFn(arr[i]);
}
pending…
for (var i = 0; i < len; i++) {
  someFn(arr[i]);
}
pending…
Cla
for (var i = 0, l = arr.length; i !== l; i++) {
  someFn(arr[i]);
}
pending…
condition
var i = len;

for (i; --i;) {
    someFn(arr[i]);
}
pending…

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Revisions

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