var submitcount=0;
var formatbut="";
 function checkFields(){
  if (document.contactform.name.value==""){
  alert("Please enter your name");
  return false;
  }
if (document.contactform.email.value==""){
  alert("Please enter your email address");
  return false;
  }
if (document.contactform.message.value==""){
  alert("Please enter your message");
  return false;
 }
    else 
   {
   if (submitcount == 0)
      {
      submitcount++;
      return true;
      }
   else 
      {
      alert("This form has already been submitted. Thanks!");
      return false;
      }
   }
}
//