Fastest array loops in Javascript

JavaScript performance comparison

Revision 335 of this test case created by Simon

Preparation code

<script>
  // Populate the base array
  var arr = [];
  for (var i = 1; i <= 1000; i++) {
    arr[i-1] = 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(arr[i]);
}
pending…
For loop, cached
for (var i = 0, len = arr.length; i < len; i++) {
  someFn(arr[i]);
}
pending…
While
var i = -1, len = arr.length;
while(++i < len) {
  someFn(arr[i]);
}
pending…
While 2
var i = 0, item;
while((item = arr[i++]) !== undefined) {
  someFn(item);
}
pending…
While 3
var l = arr.length;
while(l--) {
  someFn(arr[l]);
}
pending…
Map
arr.map(function (item) {
  someFn(item);
});
pending…
forEach
arr.forEach(function (item) {
  someFn(item);
});
pending…
for loop, assigning value
for (var i = 0, item; (item = arr[i]); i++) {
  someFn(item);
}
pending…

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Revisions

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