moment.js countdown prototype

countdown.js

var countdown = function(end) {
    var start = moment();    
    var d = end.diff(start);
    var dur = moment.duration(d);
    
    var days = dur.days();
    var hours = dur.hours();
    var minutes = dur.minutes();
    var seconds = dur.seconds();
    $("#countdown").html(days + " days " + hours + " hours " + minutes + " minutes " + seconds + " seconds ");
};

$(function(){
    var e = moment().add("days", 22);
    countdown(e);
    setInterval(function() {
        countdown(e);
    }, 1000);
});