for vs forEach

JavaScript performance comparison

Revision 89 of this test case created

Info

Is it faster to use the native forEach or just loop with for?

Preparation code

<script>
  var i, values = [],
      sum = 0;
  for (i = 0; i < 10000; i++) {
   values[i] = i;
  }
 
  function add(val) {
   sum += val;
  }

Array.prototype.forEach2 = function (func) {
  for (var i = 0, count = this.length; i < count; i++) {
    func.call(this, this[i]);
  }
};
</script>

Test runner

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Testing in unknown unknown
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…
Closured for-loop
(function() {
  for (var i = 0, count = values.length; i < count; i++) {
    add(values[i]);
  }
})();
pending…
Polyfilled forEach
values.forEach2(add);
pending…
for loop, creating scope
for (i = 0; i < values.length; i++) {
  (function(i) {
    add(values[i]);
  })(i)
}
pending…

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