setInterval(function(){
var date = new Date();
var format = "YYYY-MMM-DD DDD";
dateConvert(date,format)
}, 1);

function dateConvert(dateobj,format){
var year = dateobj.getFullYear();
var month= ("0" + (dateobj.getMonth()+1)).slice(-2);
var date = ("0" + dateobj.getDate()).slice(-2);
var hours = ("0" + dateobj.getHours()).slice(-2);
var minutes = ("0" + dateobj.getMinutes()).slice(-2);
var seconds = ("0" + dateobj.getSeconds()).slice(-2);
var day = dateobj.getDay();
var months = ["1","2","3","4","5","6","7","8","9","10","11","12"];
var converted_date = "";

switch(format){
case "YYYY-MM-DD":
converted_date = year + "-" + month + "-" + date;
break;
case "YYYY-MMM-DD DDD":
converted_date = year + "-" + months[parseInt(month)-1] + "-" + date
+ " " + hours + ":" + minutes + ":" + seconds;
break;
}
//return converted_date;
// to show it I used innerHTMl in a <p> tag
document.getElementById("example").innerHTML = converted_date;
}