Math.round vs hack

JavaScript performance comparison

Revision 74 of this test case created by Justin

Preparation code

<script>
  var somenum = -500 + (Math.random() * 1000);
  var rounded;
</script>
    

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Testing in CCBot 2.0.0 / Other 0.0.0
Test Ops/sec
"proper" rounding
function r(n) {
  return Math.round(n);
}
rounded = r(somenum);
pending…
Hack rounding
function r(n) {
 return ~~ (0.5 + n);
}
rounded = r(somenum);
pending…
Proper hack rounding
function r(n) {
  return ~~ (somenum + (somenum > 0 ? .5 : -.5));
}
rounded = r(somenum);
pending…
Hack with bitwise OR
function r(n) {
  return (0.5 + n) | 0;
}
rounded = r(somenum);
pending…
Hack with bitwise shift
function r(n) {
  return (0.5 + n) << 0;
}
rounded = r(somenum);
pending…
no func call
rounded = (0.5 + somenum) << 0;
pending…

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Revisions

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