for loop without comparison

JavaScript performance comparison

Revision 124 of this test case created by Kamil

Preparation code

for (var i = arr.length; i--;) {
  arr[i] *= 2;
}
      
<script>
Benchmark.prototype.setup = function() {
  var double = function(x){ return x*2; };
  var arr = [];
  for (var i = 0; i < 1000; i++) {
    arr[i] = Math.random();
  }

};
</script>

Preparation code output

for (var i = arr.length; i--;) { arr[i] *= 2; }

Test runner

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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…
Implicit Postfix
for (var i = 0; i < arr.length; ) {
  arr[i++] *= 2;
}
pending…
Array forEach
arr.forEach(function(el, idx) {
  arr[idx] *= 2;
});
pending…
cached + function
for (var i = 0, len = arr.length; i < len; i++) {
  arr[i] = double(arr[i]);
}
pending…
Array map + declared function
arr.map(double);
pending…

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Revisions

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0 Comments

for (var i = arr.length; i--;) { arr[i] *= 2; }