Add Commas to JavaScript output

I'm using the following script to count upward at an interval and it works perfectly. However, I'd like it to format the number with commas (56,181,995 instead of 56181995).

var START_DATE = new Date("July 27, 2010 13:30:00"); // put in the starting date here
var INTERVAL = 1; // in seconds
var INCREMENT = 2; // increase per tick
var START_VALUE = 101; // initial value when it's the start date
var count = 0;

window.onload = function()
{
var msInterval = INTERVAL * 1000;
var now = new Date();
count = parseInt((now - START_DATE)/msInterval) * INCREMENT + START_VALUE;
document.getElementById('counter').innerHTML = count;
se开发者_开发百科tInterval("count += INCREMENT; document.getElementById('counter').innerHTML = count;", msInterval);
}

I thought I had found an answer here on SO but I can't get it to work:

How to print a number with commas as thousands separators in JavaScript

(1234567890).toLocaleString();

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;
}

http://www.mredkj.com/javascript/nfbasic.html

To integrate:

var msInterval = INTERVAL * 1000;
var now = new Date();
count = parseInt((now - START_DATE)/msInterval) * INCREMENT + START_VALUE;
document.getElementById('counter').innerHTML = addCommas(count);
setInterval("count += INCREMENT; document.getElementById('counter').innerHTML = addCommas(count);", msInterval);

formatting - How can I format numbers as money in JavaScript?

using this SO post on formatting money as a basis, you can re-engineer this to work for just comma separation

here's an example - http://jsfiddle.net/pxfunc/etfjW/

You can extend the javascript Number type to include a commaSeparated formatter method like so:

Number.prototype.commaSeparated = function() {
    var n = this,
        t = ",",
        s = n < 0 ? "-" : "",
        i = parseInt(n = Math.abs(+n || 0)) + "",
        j = (j = i.length) > 3 ? j % 3 : 0;
    return s + (j ? i.substr(0, j) + t : "") + i.substr(j).replace(/(\d{3})(?=\d)/g, "$1" + t);
};

then call it like so

count.commaSeparated();

or

(1234567890).commaSeparated();

function addCommas(str){
   var arr,int,dec;
   str += '';

   arr = str.split('.');
   int = arr[0] + '';
   dec = arr.length>1?'.'+arr[1]:'';

   return int.replace(/(\d)(?=(\d{3})+$)/g,"$1,") + dec;
}