for loop speed i++ vs ++i

JavaScript performance comparison

Revision 122 of this test case created by

Preparation code


      
      <script>
Benchmark.prototype.setup = function() {
  var arr = [];
  for (var i = 0; i < 1000; i++) {
    arr[i] = Math.random();
  }

};
</script>

Test runner

Warning! For accurate results, please disable Firebug before running the tests. (Why?)

Java applet disabled.

Testing in CCBot 2.0.0 / Other 0.0.0
Test Ops/sec
i++ test
for (var i = 0, len = arr.length; i < len; i++) {
  arr[i] *= 2;
}
pending…
++i test
for (var i = 0, len = arr.length; i < len; ++i) {
  arr[i] *= 2;
}
pending…
Rev 1
for (var i = arr.length-1; i >= 0; i--) {
  arr[i] *= 2;
}
pending…
Rev 2
for (var i = arr.length-1; i != 0; i--) {
  arr[i] *= 2;
}
pending…
Rev 3
for (var i = arr.length-1; i != -1; --i) {
  arr[i] *= 2;
}
pending…
Rev Rev
for (var i = -arr.length; i == 0; ++i) {
  arr[-i] *= 2;
}
pending…
While Rev
var len = arr.length;
while (len--) {
  arr[len] *= 2;
}
pending…
While Rev Fix
var len = -arr.length;
while (len++) {
  arr[-len] *= 2;
}
pending…
standard loop
for (var i = 0; i < arr.length; i++) {
  arr[-i] *= 2;
}
pending…
forwhile hybrid
var len = arr.length;
for (var i = len ; i--;) {
  arr[-i] *= 2;
}
pending…

Compare results of other browsers

Revisions

You can edit these tests or add even more tests to this page by appending /edit to the URL.

0 Comments