Many times when you write a number in your site you want to add commas and format the number, for example: instead of 1000000 I want to my user to see 1,000,000.

Using JavaScript this is very simple task, you can also extend this code example to a Plugin inside JavaScript Lib - How To Write JavaScript \ JQuery Plugins

First I’m looking for . char inside the number (we don’t want to split this…) and after that using Regex just adding comma after 3 chars.

function addCommas(nStr) {
    nStr += '';
    var x = nStr.split('.');
    var x1 = x[0];
    var x2 = x.length > 1 ? '.' + x[1] : '';
    var rgx = /(\d+)(\d{3})/;
    while (rgx.test(x1)) {
        x1 = x1.replace(rgx, '$1' + ',' + '$2');
    }
    return x1 + x2;
}

Example:

addCommas(1000000);
// 1,000,000
 
addCommas(1234.1111);
// 1,234.1111
 
addCommas('9999999.1234');
// 9,999,999.1234
 
addCommas(-500000.00);
// -500,000.00