Packed vs. holey arrays

JavaScript performance comparison

Revision 3 of this test case created

Preparation code

 
<script>
  Benchmark.prototype.setup = function() {
    var packed_array = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
    
    var holey_array1 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
    delete holey_array1[0];
    
    var holey_array2 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
    holey_array2[13] = 0;
    
    var holey_array3 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, /* hole */, 11];
    
    function packed_sum() {
      var sum = 0;
      for (var i = 0; i < packed_array.length; i++) {
        sum += packed_array[i];
      }
    }
    
    function holey_sum1() {
      var sum = 0;
      for (var i = 1; i < holey_array1.length; i++) {
        sum += holey_array1[i];
      }
    }
    
    function holey_sum2() {
      var sum = 0;
      for (var i = 0; i <= 10; i++) {
        sum += holey_array2[i];
      }
      sum += holey_array2[13];
    }
    
    function holey_sum3() {
      var sum = 0;
      for (var i = 0; i < 10; i++) {
        sum += holey_array3[i];
      }
      sum += holey_array3[11];
    }
  };
</script>

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Testing in unknown unknown
Test Ops/sec
Packed array sum
 
packed_sum();
 pending…
Holey array sum 1
 
holey_sum1();
 pending…
Holey array sum 2
 
holey_sum2();
 pending…
Holey array sum 3
 
holey_sum3();
 pending…

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