Gaussian/banker's rounding in JavaScript

Question

I have been using Math.Round(myNumber, MidpointRounding.ToEven) in C# to do my server-side rounding, however, the user needs to know \'live\' what the result of

Answer 1

The accepted answer does round to a given number of places. In the process it calls toFixed which converts the number to a string. Since this is expensive, I offer the solution below. It rounds a number ending in 0.5 to the nearest even number. It does not handle rounding to an arbitrary number of places.

function even_p(n){
  return (0===(n%2));
};

function bankers_round(x){
    var r = Math.round(x);
    return (((((x>0)?x:(-x))%1)===0.5)?((even_p(r))?r:(r-1)):r);
};