Format numbers in JavaScript similar to C#

Question

Is there a simple way to format numbers in JavaScript, similar to the formatting methods available in C# (or VB.NET) via ToString(\"format_provider\") or

Answer 1

I wrote a simple function (not yet another jQuery plugin needed!!) that converts a number to a decimal separated string or an empty string if the number wasn't a number to begin with:

function format(x) {
    return isNaN(x)?"":x.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");
}

format(578999); results in 578,999

format(10); results in 10

if you want to have a decimal point instead of a comma simply replace the comma in the code with a decimal point.

One of the comments correctly stated this only works for integers, with a few small adaptions you can make it work for floating points as well:

function format(x) {
    if(isNaN(x))return "";

    n= x.toString().split('.');
    return n[0].replace(/\B(?=(\d{3})+(?!\d))/g, ",")+(n.length>1?"."+n[1]:"");
}