Info

Compare various ways of rounding.

Preparation code

 
<script>
  Benchmark.prototype.setup = function() {
    var somenum = -500 + (Math.random() * 1000), rounded = 1000;
  };

  Benchmark.prototype.teardown = function() {
    var round, or, not, left, result;
    round = Math.round(somenum);
    or = (somenum + (somenum > 0 ? .5 : -.5)) | 0;
    not = ~~ (somenum + (somenum > 0 ? .5 : -.5));
    left = (somenum + (somenum > 0 ? .5 : -.5)) << 0;
    if(round == or && or == not && not == left) result = ('all values = '+round+' from: '+somenum);
    else result = (['values do not match!','round:'+round,'or'+or,'not'+not,'left'+left, 'from:'+somenum].join('; '));
    if(window.console && console.log) console.log(result);
  };
</script>

Test runner

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Java applet disabled.

rounded = Math.round(somenum);

rounded = ~~ (somenum + (somenum > 0 ? .5 : -.5));

rounded = (somenum + (somenum > 0 ? .5 : -.5)) | 0;

rounded = (somenum + (somenum > 0 ? .5 : -.5)) << 0;

rounded = Math.round(somenum);

rounded = ~~ (somenum + (somenum > 0 ? .5 : -.5));

rounded = (somenum + (somenum > 0 ? .5 : -.5)) | 0;

rounded = (somenum + (somenum > 0 ? .5 : -.5)) << 0;

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Revisions

You can edit these tests or add even more tests to this page by appending /edit to the URL. Here’s a list of current revisions for this page:

• Revision 1: published by Jim Montgomery on 6th November 2011
• Revision 2: published on 25th April 2013

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