for vs forEach

JavaScript performance comparison

Revision 406 of this test case created by Amuseum

Preparation code

<script>
  var i, values = [],
      sum = 0;
  for (i = 0; i < 10000; i++) {
   values[i] = i;
  }
  
  function add(val) {
   sum += val;
  }
</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…
forEach more local
(function() {
  var sum = 0;
  values.forEach(function(val) {
    sum += val;
  });
})();
pending…
for loop, local vars
for (var i = 0, len = values.length; i < len; i++) {
  add(values[i]);
}
pending…
for in
for (i in values) {
  add(values[i]);
}
pending…
for of
for (i of values) {
  add(i);
}
pending…
forEach anonymous
values.forEach(function(val) {
  sum += val;
});
pending…
for loop, localize array
for (var i = 0, v = values, len = v.length; i < len; i++) {
  add(v[i]);
}
pending…
map function
function map(array, func) {
  for (var i = 0, a = array, len = a.length; i < len; i++) {
    func(a[i]);
  }
}
map(values, add);
pending…
map, local func
function map(array, func) {
  for (var i = 0, a = array, len = a.length, f = func; i < len; i++) {
    f(a[i]);
  }
}
map(values, add);
pending…
array.reduce()
add = function(sum, addend) {
  return sum + addend;
}
sum = values.reduce(add);
pending…
array.map
values.map(add);
pending…
for loop, localize function
for (var i = 0, a = values, l = a.length, f = add; i < l; i++) {
  f(a[i]);
}
pending…

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