caching length

JavaScript performance comparison

Revision 83 of this test case created by Ömer Kaşdarma

Preparation code 


      
      <script>

        Benchmark.prototype.setup = function() {

          
  var arr = [];
  for (var i = 0; i < 1000; i++) {
    arr[i] = Math.random();
  }

        
  };


      
</script>

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Testing in CCBot 2.0.0 / Other 0.0.0
Test Ops/sec
cached 
for (var i = 0, len = arr.length; i < len; i++) {
  arr[i] *= 2;
}
 pending…
not cached 
for (var i = 0; i < arr.length; i++) {
  arr[i] *= 2;
}
 pending…
u wot m8 
var len = 2;
len *= arr.length;
len -= len / 2;
for (var i = 0; i < len; i++) {
  arr[i] *= 2;
}
 pending…
while loop 
var len = arr.length;
while (len--) {
  arr[len] *= 2;
}
 pending…
do-while loop 
var len = arr.length;
do {
  arr[len] *= 2;
} while (len--);
 pending…
Prefix Increment 
for (var i = 0; i < arr.length; ++i) {
  arr[i] *= 2;
}
 pending…
Prefix + Cached 
for (var i = 0, len = arr.length; i < len; ++i) {
  arr[i] *= 2;
}
 pending…
Array map 
arr.map(function(el) {
  return el * 2;
});
 pending…
forward While 
var len = arr.length;
var head = arr.length - 1;
while (len--) {
  var i = head - len
  arr[i] *= 2;
}
 pending…
for decrement wtf style 
for (var i = arr.length; i--;) {
  arr[i] *= 2;
}
 pending…

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Revisions

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