for vs forEach

JavaScript performance comparison

Revision 245 of this test case created by Jerry

Preparation code

<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>

      
<script>
Benchmark.prototype.setup = function() {
  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)
        }
      }
    }
  };

};

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

};
</script>

Preparation code output

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

Test runner

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Testing in CCBot 2.0.0 / Other 0.0.0
Test Ops/sec
for, = ... +
for (i = 0; i < values.length; ++i) {
  sum = sum + values[i];
}
pending…
for, callback
for (i = 0; i < values.length; ++i) {
  add(values[i], i, values);
}
pending…
for, callback.call
for (i = 0; i < values.length; ++i) {
  add.call(context, values[i], i, values);
}
pending…
forEach
values.forEach(function(val) {
  sum += val;
});
pending…
$.each
$.each(values, function(key, value) {
  sum += value;
});
pending…
for ... in
for (i in values) {
  sum += values[i];
}
pending…
custom forEach
values.forEach2(function(val) {
  sum += val;
});
pending…
for, temoin
for (i = 0; i < values.length; ++i) {
  sum += values[i];
}
pending…
underscore
_.each(values, function(val) {
  sum += val;
})
pending…
forEach 2
values.forEach(add);
pending…
for
for (i = 0; i < values.length; ++i) {
  sum += values[i];
}
pending…
for, cached length
length = values.length;
for (i = 0; i < length; ++i) {
  sum += values[i];
}
pending…
for, decrement
for (i = values.length - 1; i >= 0; --i) {
  sum += values[i];
}
pending…
for, decrement condition
for (i = values.length; --i;) {
  sum += values[i];
}
pending…
for, post increment
for (i = 0; i < values.length; i++) {
  sum += values[i];
}
pending…
for, assignment condition
for (i = 0;
  (value = values[i]) != null; ++i) {
  sum += value;
}
pending…

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Revisions

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