Question

66

rated 0 times [ 72] [ 6] / answers: 1 / hits: 33727 / 15 Years ago, sun, january 24, 2010, 12:00:00

I want to truncate a number in javascript, that means to cut away the decimal part:

trunc ( 2.6 ) == 2

trunc (-2.6 ) == -2

After heavy benchmarking my answer is:

 function trunc (n) {

    return ~~n;

 }

 

 // or  



 function trunc1 (n) {

    return n | 0;

 }

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answered 15 Years ago kaya · Accepted Answer

As an addition to the @Daniel's answer, if you want to truncate always towards zero, you can:

function truncate(n) {

  return n | 0; // bitwise operators convert operands to 32-bit integers

}

Or:

function truncate(n) {

  return Math[n > 0 ? floor : ceil](n);

}

Both will give you the right results for both, positive and negative numbers:

truncate(-3.25) == -3;

truncate(3.25) == 3;