for vs forEach

JavaScript performance comparison

Revision 53 of this test case created by Jean Vincent

Preparation code

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js">
</script>
      
<script>
Benchmark.prototype.setup = function() {
  var i,
      value,
      length,
      values = [],
      sum = 0,
      context = values;
  
  
  for (i = 0; i < 10000; i++) {
      values[i] = i + 1;
  }
  
  function add(val) {
      sum += val;
  }

};

Benchmark.prototype.teardown = function() {
  i = 0;
  value = 0;
  length = 0;
  values = [];
  sum = 0;

};
</script>

Test runner

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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++) {
    sum += values[i];
}
pending…
for loop, cached length
length = values.length;
for (i = 0; i < length; i++) {
    sum += values[i];
}
pending…
for loop, reverse
for (i = values.length - 1; i >= 0; i--) {
    sum += values[i];
}
pending…
for loop, cached length, callback
length = values.length;
for (i = 0; i < length; i++) {
    add(values[i], i, values);
}
pending…
for loop, cached length, callback.call
length = values.length;
for (i = 0; i < length; i++) {
    add.call(context, values[i], i, values);
}
pending…
$.each
$.each(values, function(key, value) {
    sum += value;
});
pending…
for ... in
for (i in values) {
    sum += values[i];
}
pending…
for loop, reverse, decrement condition
for (i = values.length; i--;) {
    sum += values[i];
}
pending…
for loop, reverse, pre-decrement
for (i = values.length - 1; i >= 0; --i) {
    sum += values[i];
}
pending…
for loop, assignment condition
for (i = 0; value = values[i]; i++) {
    sum += value;
}
pending…
for loop, assignment condition, reversed
for (i = values.length - 1; value = values[i]; i--) {
    sum += value;
}
pending…
for loop, assignment condition, callback
for (i = 0; value = values[i]; i++) {
    add(value, i, values);
}
pending…
for loop, assignment condition, callback.call
for (i = 0; value = values[i]; i++) {
    add.call(context, value, i, values);
}
pending…
while lopp pre-increment
var i = -1, l = values.length >> 0;

while( ++i < l ) sum += values[ i ];
pending…
while loop, reverse, pre-decrement
var i = values.length >> 0;

while( i ) sum += values[ --i ];
pending…
unfolded while loop
var i = -1, l = ( ( ( values.length / 13 ) >> 0 ) * 13 ) >> 0;

while( ++i < l ) {
  sum += values[ i ]
    + values[ ++i ] + values[ ++i ] + values[ ++i ] + values[ ++i ]
    + values[ ++i ] + values[ ++i ] + values[ ++i ] + values[ ++i ]
    + values[ ++i ] + values[ ++i ] + values[ ++i ] + values[ ++i ]
  ;
}

while ( ++i < values.length ) sum += values[ i ];
pending…
while loop, 10000 hard-coded
var i = -1;

while( ++i < 10000 ) sum += values[ i ];
pending…

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Revisions

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