jsPerf.app is an online JavaScript performance benchmark test runner & jsperf.com mirror. It is a complete rewrite in homage to the once excellent jsperf.com now with hopefully a more modern & maintainable codebase.
jsperf.com URLs are mirrored at the same path, e.g:
https://jsperf.com/negative-modulo/2
Can be accessed at:
https://jsperf.app/negative-modulo/2
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...
<script>
var cached_Math_round = Math.round;
var somenum = -500 + (Math.random() * 1000);
var rounded;
</script>Ready to run.
| Test | Ops/sec | |
|---|---|---|
| "proper" rounding | | ready |
| Hack rounding | | ready |
| Proper hack rounding | | ready |
| Hack with bitwise OR | | ready |
| Hack with bitwise shift | | ready |
| Proper way with cached round function | | ready |
You can edit these tests or add more tests to this page by appending /edit to the URL.