for vs array-foreach

JavaScript performance comparison

Revision 4 of this test case created by John-David Dalton and last updated

Preparation code

 
<script>
Benchmark.prototype.setup = function() {
    var array = Array(31).join('x').split('');
   
    function callback(value, index, object) {
      return value + index;
    }
   
    function customForEach(array, callback, thisArg) {
      var fn = callback,
          index = -1,
          length = array.length;
   
      while (++index < length) {
        if (callback(array[index], index, array) === false) {
          break;
        }
      }
      return array;
    }
};
</script>

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Testing in unknown unknown
Test Ops/sec
custom forEach
customForEach(array, callback);
pending…
Array#forEach
array.forEach(callback);
pending…

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1 comment

John-David Dalton (revision owner) commented :

The point of this test is to show that by creating your own custom forEach-lite implementation you can get better performance over native.

Many times you don't need to support all of the functionality/edge cases of the native method and that allows you to gain performance/custom-functionality and save code because you no longer need to have an ES5 compliant fallback.

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