Caching Array Length

JavaScript performance comparison

Revision 7 of this test case created

Preparation code

 
<script>
Benchmark.prototype.setup = function() {
    var theArray = ["", 56,
      function() {},
      93, "lalala", {}
    ];
    var copyOfTheArray = [];
};
</script>

Test runner

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Testing in unknown unknown
Test Ops/sec
For with caching
var len = theArray.length;
for (var i = 0; i < len; i++) {
  copyOfTheArray[i] = theArray[i];
}
pending…
For without caching
for (var i = 0; i < theArray.length; i++) {
  copyOfTheArray[i] = theArray[i];
}
pending…
For in
for (var i in theArray) {
  copyOfTheArray[i] = theArray[i];
}
pending…
Foreach
theArray.forEach(function(it, idx){
  copyOfTheArray[idx] = it;
});
pending…

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