for vs forEach (v248)

Revision 248 of this benchmark created by Per on

Preparation HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js">
</script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.7.0/underscore-min.js">
</script>

Setup

var i,
    value,
    length,
    values = [],
    sum = 0,
    context = values;
  
  for (i = 0; i < 10000; ++i) {
    values[i] = Math.random();
  }
  
  function add(val) {
    sum += val;
  }
  
  // custom forEach
  Array.prototype.forEach2 = function(fn, c) {
  
    //if (this === void 0 || this === null || typeof fn !== 'function') throw new TypeError;
  
    var t = Object(this),
      len = t.length >>> 0,
      nc = (c === void 0 || c === null);
  
    for (var i = 0; i < len; ++i) {
      if (i in t) {
        if (nc) {
          fn(t[i], i, t)
        } else {
          fn.call(c, t[i], i, t)
        }
      }
    }
  };

Teardown



            i = 0;
  value = 0;
  length = 0;
  values = [];
  sum = 0;

Test runner

Ready to run.

Testing in
TestOps/sec
for
for (i = 0; i < values.length; ++i) {
  sum += values[i];
}
ready
for, cached length
length = values.length;
for (i = 0; i < length; ++i) {
  sum += values[i];
}
ready
for, decrement
for (i = values.length - 1; i >= 0; --i) {
  sum += values[i];
}
ready
for, decrement condition
for (i = values.length; --i;) {
  sum += values[i];
}
ready
for, post increment
for (i = 0; i < values.length; i++) {
  sum += values[i];
}
ready
for, assignment condition
for (i = 0;
  (value = values[i]) != null; ++i) {
  sum += value;
}
ready
for, = ... +
for (i = 0; i < values.length; ++i) {
  sum = sum + values[i];
}
ready
for, callback
for (i = 0; i < values.length; ++i) {
  add(values[i], i, values);
}
ready
for, callback.call
for (i = 0; i < values.length; ++i) {
  add.call(context, values[i], i, values);
}
ready
forEach
values.forEach(function(val) {
  sum += val;
});
ready
$.each
$.each(values, function(key, value) {
  sum += value;
});
ready
for ... in
for (i in values) {
  sum += values[i];
}
ready
custom forEach
values.forEach2(function(val) {
  sum += val;
});
ready
for, temoin
for (i = 0; i < values.length; ++i) {
  sum += values[i];
}
ready
underscore
_.each(values, function(val) {
  sum += val;
})
ready
forEach 2
values.forEach(add);
ready
loop unrolling
var rest = values.length % 16;
for (j = 0; j < rest; j++) {
  sum += values[j];
}

var sumA = 0;
for (i = values.length - j; i != 0; i = i - 16) {
  sumA += values[j++];
  sum  += values[j++];
  sumA += values[j++];
  sum  += values[j++];
  sumA += values[j++];
  sum  += values[j++];
  sumA += values[j++];
  sum  += values[j++];
  sumA += values[j++];
  sum  += values[j++];
  sumA += values[j++];
  sum  += values[j++];
  sumA += values[j++];
  sum  += values[j++];
  sumA += values[j++];
  sum  += values[j++];
}

sum += sumA;
ready
half loop
var halfLength = values.length/2 ;
for (i = 0; i < halfLength; i++) {
  sum += values[i] + values[values.length-1-i];
}
ready

Revisions

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