Javascript Date Countdown

function countdown(yr,mon,d,h,m,pastmessage,target){
 //yr,mon,d,h,m are the Year, Month, Day, Hour, and Minute of the date the future event occurs
 //pastmessage is the message to display when the event has already happened
 //target is the target element to write the output to
 var today=new Date();
 var futuredate=new Date(yr,mon-1,d,h,m); //don't care why but the month has to be decremented
 dd=futuredate-today; //this should be the difference in the two dates in milliseconds
 dday=Math.floor(dd/(60*60*1000*24)*1); //find the number of days in dd
 dhour=Math.floor((dd%(60*60*1000*24))/(60*60*1000)*1); //find the number of hours in dd
 dmin=Math.floor(((dd%(60*60*1000*24))%(60*60*1000))/(60*1000)*1); //find the number of minutes in dd
 var wholedmin=dmin;if (dmin < 10){wholedmin="0"+dmin;} //convert to 2 digits if necessary
 dsec=Math.floor((((dd%(60*60*1000*24))%(60*60*1000))%(60*1000))/1000*1); //find the number of seconds in dd
 var wholedsec=dsec;if (dsec < 10){wholedsec="0"+dsec;} //convert to 2 digits if necessary
 if(futuredate<=today){
  document.getElementById(target).innerHTML=pastmessage; //write this if the date is past
 }
 else {
  document.getElementById(target).innerHTML= dday+ " days, "+dhour+":"+wholedmin+":"+wholedsec; //write this is futuredate is in the future
}}
</script>
<div style="display:table-cell;background-image:url('http://www.highsnobiety.com/files/2013/01/star-wars-episode-7-vii.jpg');background-size:100% 100%;height:175px;width:276px;padding:5%;vertical-align:bottom;text-align:center;color:white;">
<!--this div is the container for the element that gets updated every second.  Reformat as needed.-->
<h1 id="starwars">
<!--this element's inner content is re-written by the countdown function --></h1>
</div>
<br />
<div style="display:table-cell;background-image:url('http://cdn.bleedingcool.net/wp-content/uploads/2013/06/doctor-who-logo-black.jpg?f6a06b');background-size:100% 100%;height:225px;width:276px;padding:5%;vertical-align:bottom;text-align:center;color:white;">
<!--this div is the container for the element that gets updated every second.  Reformat as needed.-->
<h1 id="drwho">
<!--this element's inner content is re-written by the countdown function --></h1>
</div>
<script>
var starwars = setInterval("countdown(2015,12,18,00,00,'It is out! Why are you not in the theater?','starwars')",1000); //this sets the starwars H1 element refreshing
var drwho = setInterval("countdown(2013,11,23,13,00,'Mind: blown.','drwho')",1000); //this sets the drwho H1 element refreshing