Math.round vs hack

JavaScript performance comparison

Revision 65 of this test case created by

Preparation code

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

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Testing in CCBot 2.0.0 / Other 0.0.0
Test Ops/sec
"proper" rounding
rounded = Math.round(somenum);
pending…
Hack rounding
rounded = ~~ (0.5 + somenum);
pending…
Proper hack rounding
rounded = ~~ (somenum + (somenum > 0 ? .5 : -.5));
pending…
Hack with bitwise OR
rounded = (0.5 + somenum) | 0;
pending…
Hack with bitwise shift
rounded = (0.5 + somenum) << 0;
pending…
xor with 0
rounded = (0.5 + somenum) ^ 0;
pending…
bitwise and
rounded = (0.5 + somenum) & 0xffff
pending…
bitwise and 64-bit
rounded = (0.5 + somenum) & 0xffffffff
pending…
parseInt
rounded = parseInt((0.5 + somenum), 10)
pending…
Window-d Math.round
rounded = mround(somenum);
pending…

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Revisions

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