function checklength(i){
         if (i<10){
          i="0"+i;}
          return i;
  }
  function clock(){
    var now = new Date();
    var hours = checklength(now.getHours());
    var minutes = checklength(now.getMinutes());
    var seconds = checklength(now.getSeconds());
    var format = 1;  //0=24 hour format, 1=12 hour format
    var time;

    if (format == 1){
      if (hours >= 12){
        if (hours ==12){
          hours = 12;
        }else {
          hours = hours-12;
        }
       time=hours+':'+minutes+':'+seconds+' PM';
      }else if(hours < 12){
           if (hours ==0){
             hours=12;
           }
       time=hours+':'+minutes+':'+seconds+' AM';
      }
    }
   if (format == 0){
      time= hours+':'+minutes+':'+seconds;
   }
   document.getElementById("clock").innerHTML="<p style = \"text-align : center;\">" + time + "</p>";
   setTimeout("clock();", 500);
  }