for vs forEach

JavaScript performance comparison

Revision 54 of this test case created by

Preparation code

<script>
  var i, values = [],
      sum = 0;
  for (i = 0; i < 10000; i++) {
   values[i] = i;
  }
  
  function add(val) {
   sum += val;
  }
</script>
      
<script>
Benchmark.prototype.setup = function() {
  Array.prototype.forEach = function(fn) {
    var i, self = this, len = self.length;
  
    for (i = 0; i < len; i++) {
      fn(self[i], i, self);
    }
  }

};
</script>

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Testing in CCBot 2.0.0 / Other 0.0.0
Test Ops/sec
forEach
values.forEach(add);
pending…
for loop, simple
for (i = 0; i < values.length; i++) {
 add(values[i]);
}
pending…
for loop, cached length
var len = values.length;
for (i = 0; i < len; i++) {
 add(values[i]);
}
pending…
for loop, reverse
for (i = values.length - 1; i >= 0; i--) {
 add(values[i]);
}
pending…
for loop, cached length, no callback
var len = values.length;
for (i = 0; i < len; i++) {
 sum += values[i];
}
pending…
for loop, cached length, using function.call and supplying index and original array
var len = values.length;
for (i = 0; i < len; i++) {
 add.call(values, values[i], i, values);
}
pending…

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Revisions

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