Info

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 code

<script>
  var somenum = (Math.random());
  var rounded;
</script>

Test runner

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rounded = Math.round(somenum);

rounded = ~~ (0.5 + somenum);

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

rounded = (0.5 + somenum) | 0;

rounded = (0.5 + somenum) << 0;

rounded = (somenum + 0.5) | 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 Tim on 26th November 2010
• Revision 3: published by Seb Lee-Delisle on 1st February 2011
• Revision 5: published by Miller Medeiros on 1st February 2011
• Revision 6: published by Paul King on 2nd February 2011
• Revision 9: published on 24th March 2011
• Revision 13: published on 20th May 2011
• Revision 14: published on 29th June 2011
• Revision 15: published on 29th June 2011
• Revision 16: published on 29th June 2011
• Revision 17: published on 29th June 2011
• Revision 18: published on 17th August 2011
• Revision 19: published by BrianMB on 19th August 2011
• Revision 20: published by BrianMB on 19th August 2011
• Revision 21: published by JeffMo on 21st August 2011
• Revision 22: published by icrusade on 2nd September 2011
• Revision 23: published on 18th September 2011
• Revision 24: published on 19th September 2011
• Revision 25: published by Nico Kruger on 19th September 2011
• Revision 26: published on 19th October 2011
• Revision 27: published by Juriy on 20th October 2011
• Revision 29: published by Hieu Le Trung on 22nd October 2011
• Revision 30: published on 11th November 2011
• Revision 31: published by george on 21st December 2011
• Revision 32: published by Andreas Wagner on 23rd January 2012
• Revision 33: published on 7th February 2012
• Revision 35: published on 28th April 2012
• Revision 36: published on 2nd May 2012
• Revision 37: published by Hao Wu on 2nd May 2012
• Revision 39: published on 20th July 2012
• Revision 40: published on 20th July 2012
• Revision 41: published on 20th July 2012
• Revision 44: published by twtwt on 4th August 2012
• Revision 45: published by Christian on 12th August 2012
• Revision 46: published on 13th August 2012
• Revision 47: published by Jakob on 5th September 2012
• Revision 48: published on 5th September 2012
• Revision 49: published on 31st October 2012
• Revision 50: published on 31st October 2012
• Revision 51: published on 19th November 2012
• Revision 52: published by Terry on 27th November 2012
• Revision 53: published by Christopher Hall on 2nd December 2012
• Revision 54: published on 16th December 2012
• Revision 55: published by Ehsan Afzali on 21st December 2012
• Revision 56: published by Ehsan Afzali on 21st December 2012
• Revision 57: published on 23rd January 2013
• Revision 58: published on 8th February 2013
• Revision 59: published by 1Pupik1989 on 20th February 2013
• Revision 60: published on 23rd February 2013
• Revision 61: published on 12th April 2013
• Revision 62: published by orwellophile 3 weeks ago
• Revision 63: published by Sergey 5 days ago
• Revision 64: published 3 days ago
• Revision 65: published 1 day ago

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