for vs for..in vs forEach (v268)

Revision 268 of this benchmark created by Sam on

Description

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

Preparation HTML

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

  function forEachFN(array,fn){
    var l = array.length;
    while(l--){fn(array[l])}
  }
  
  var values2 = JSON.parse(JSON.stringify(values));
  values2.forEach = function(fn){
    var l = this.length;
    while(l--){fn(this[l]);}
  }

</script>

Test runner

Ready to run.

Testing in
TestOps/sec
forEach
values.forEach(add);
ready
for loop, simple
for (i = 0; i < values.length; i++) {
 add(values[i]);
}
ready
for loop, cached length
var len = values.length;
for (i = 0; i < len; i++) {
 add(values[i]);
}
ready
for..in loop
for (i in values) {
 add(values[i]);
}
ready
forEach more local
(function() {
 var sum = 0;
 values.forEach(function(val) {
  sum += val;
 });
})();
ready
while --
var l = values.length;
while(l--){ add(values[l]); }
ready
forEach as function
forEachFN(values, add);
ready
forEach as prototype
values2.forEach(add)
ready

Revisions

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