for vs forEach

JavaScript performance comparison

Revision 49 of this test case created by smith

Preparation code

<script src="https://code.jquery.com/jquery-1.8.2.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;
  }
  function addEach(k, val) {
      sum += val;
  }
  
  var toString = Object.prototype.toString;
  
  function isArray(obj) {
  	return toString.call(obj) === '[object Array]';
  }
  
  function isObject(obj) {
  	return toString.call(obj) === '[object Object]';
  }
  
  function isString(obj) {
  	return toString.call(obj) === '[object String]';
  }
  
  function each(obj, iterator) {
  	var key, length;
  	if (!obj) {
  		return;
  	}
  	length = obj.length;
  
  	if (isArray(obj) || isString(obj)) {
  		for(key = 0; key < length; key += 1) {
  			iterator(obj[key], key, obj);
  		}
  		return obj;
  	}
  
  	if (isObject(obj)) {
  		for(key in obj) {
  			if (obj.hasOwnProperty(key)) {
  				iterator(obj[key], key, obj);
  			}
  		}
  		return obj;
  	}
  
  	return obj;
  };

};

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, cached length, callback
var arr = values,
    length = arr.length;
for (var i = 0; i < length; i++) {
    add(arr[i], i, arr);
}
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, addEach);
pending…
for loop, assignment condition, callback
for (i = 0; (value = values[i]) !== undefined; i++) {
    add(value, i, values);
}
pending…
for loop, assignment condition, callback.call
for (i = 0; (value = values[i]) !== undefined; i++) {
    add.call(context, value, i, values);
}
pending…
native map function
values.map(add);
pending…
new each
each(values, add);
pending…

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Revisions

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