Math.round vs hack

JavaScript performance comparison

Revision 22 of this test case created by icrusade

Preparation code

<script>
  var mround = Math.round;
  var hround = function(n){
    return ~~ (0.5 + n)
  };
  var phround = function(n){
    return ~~ (n + (n > 0 ? .5 : -.5));
  };
  var orround = function(n){
    return (0.5 + n) | 0;
  };
  var shround = function(n){
    return (0.5 + n) << 0;
  };
  
  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
rounded = mround(somenum);
pending…
Hack rounding
rounded = hround(somenum);
pending…
Proper hack rounding
rounded = phround(somenum);
pending…
Hack with bitwise OR
rounded = orround(somenum);
pending…
Hack with bitwise shift
rounded = shround(somenum);
pending…

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Revisions

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