How do I format javascript results with commas and decimals?

Question

I've searched for and reviewed other posts on this site related to this question, but being someone in the very early stages of trying to learn javascript, I don't know how to apply what I'm seeing.

I need the result calculations located here ( http://jsfiddle.net/hughett/xwnbepzr/ ) to be formatted with decimals and commas. In other words, the results below should be formatted like the following:

Watts saved per lamp 53
Total watts saved 5,300 (instead of 5300)
Total kilowatts saved 5
KWh saved per year 22,260 (instead of 22260)
Cost savings per year $3,339.00 (instead of 3339)

$(function(){
var tws = 0;
var tks = 0;
var kspy = 0;
var wspl = 0;
var cspy = 0;
var sp = 0;
var ror = 0;
$("input[name=old_watts], input[name=new_watts]").blur(function(e){
    calc_wspl();
});
$("input[name=n]").blur(function(e){
    calc_tws();
});
$("input[name=hours], input[name=days], input[name=weeks]").blur(function(e){
    calc_kspy();
});
$("input[name=cost]").blur(function(e){
    calc_cspy();
});
$("input[name=upgrade]").blur(function(e){
    calc_summary();
})

function calc_wspl(){
    wspl= parseFloat($("input[name=old_watts]").val() ) - parseFloat( $("input[name=new_watts]").val() );
    $(".wspl").html(wspl > 0 ? wspl : '');
    calc_tws();
}
function calc_tws() {
    tws = wspl * parseFloat( $("input[name=n]").val() );
    $(".tws").html(tws > 0 ? tws : '');
    $(".tks").html(tws > 0 ? parseInt(tws / 1000) : '');
    calc_kspy();
}
function calc_kspy() {
    if (tws > 0)
    {
        kspy = parseFloat($("input[name=hours]").val() ) * parseFloat($("input[name=days]").val() ) * parseFloat($("input[name=weeks]").val() ) * tws / 1000;
        $(".kspy").html(kspy > 0 ? kspy : '');
        calc_cspy();
    }
}
function calc_cspy(){
    cspy = parseFloat($("input[name=cost]").val() ) * kspy;
    $(".cspy").html(cspy >= 1 ? "$" + parseInt(cspy) : '');
    calc_summary();
}
function calc_summary(){
    if (cspy) {
        sp = parseFloat($("input[name=upgrade]").val()) / cspy;
        if (sp) {
            sp = (sp < 100) ? sp.toString().substring(0, 4) : sp;
            $(".sp").html(sp + " year" + ((sp > 1) ? 's': ''));
            $(".ror").html(parseInt((1/sp) * 100) + '%');
        }
    }
}