Fastest array loops in Javascript

JavaScript performance comparison

Revision 368 of this test case created by

Preparation code

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

  function someFn (ix) {
      return ix + 1 / 2;
  }
</script>
    

Test runner

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Testing in CCBot 2.0.0 / Other 0.0.0
Test Ops/sec
For loop, basic
for( var i = 0; i < arr.length; i++ ) {
    someFn(i);
}
pending…
While loop, basic
var i = 0;
while(i < arr.length) {
    someFn(i);
    i++;
}
pending…
For loop, cached
for (var i = 0, len = arr.length; i < len; i++) {
    someFn(i);
}
pending…
While loop, cached
var i = 0;
var len = arr.length;
while(i < len) {
    someFn(i);
    i++;
}
pending…
For loop, i--
for (var i = arr.length - 1; i > -1; i--) {
    someFn(i);
}
pending…
While loop, i--
var i = arr.length - 1;
while(i > -1) {
    someFn(i);
    i--;
}
pending…

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Revisions

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