Fastest array loops in Javascript

JavaScript performance comparison

Revision 497 of this test case created by Samir

Preparation code

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

  function someFn(ix) {
    return ix * 5 + 1 / 3 * 8;
  }
</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…
For loop, cached
for (var i = 0, len = arr.length; i < len; i++) {
  someFn(i);
}
pending…
For loop, i++
for (var i = 0, len = arr.length; i < len; i += 1) {
  someFn(i);
}
pending…
For loop reverse
for (var i = arr.length; i--;) {
  someFn(i);
}
pending…

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Revisions

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