Math.round vs hack (v40)

Revision 40 of this benchmark created on

Description

Math.round() has a function call overhead, so using the ~~ hack (truncate towards 0) and adding 0.5 works quicker, but if you want to handle negative numbers too then you have to check whether to add or subtract 0.5 .... and this wipes out the speed advantage. So ~~(0.5+num) is only worth it if you know your numbers always have the same sign...

Preparation HTML

<canvas id="canvas1" width="500" height="500"></canvas>
<script>
  var can = document.getElementById('canvas1');
  var ctx = can.getContext('2d');
  
  
 
</script>

Test runner

Ready to run.

Testing in
TestOps/sec
"proper" rounding

var i = 0;
for(i = 0 ; i < 1000 ; ++i)
{
}
ready
Hack rounding
ctx.save();
ctx.restore();
ready

Revisions

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