How to round using ROUND HALF UP. Rounding mode that most of us were taught in grade school

Question

how to round using ROUND HALF UP in javascript? I am using Prototype JavaScript framework version 1.5.1_rc3, so I prefer to use it if available. If not, I appreciate also if you share it.

Any guidance is appreciated.

Answer 1

The Math.round() will round up when n >= 5 else round down

Examples:

Math.round(20.49);// 20

Math.round(20.5);// 21

Math.round(-20.5);// -20

Math.round(-20.51);// -21

_{Note: The examples were taken from the link above}

Native functions don't bite, my advice is to try to always try to use them whenever possible. They are faster and do the same job after all

Answer 2

Consider:

if (!Number.prototype.round) {
  Number.prototype.round = function() {
    return Math.round(this);
  }
}

var x = 5.49;
alert(x.round()); // 5
alert((7.499).round()); // 7