function changeInput(input_id, checktext){
   if(checktext == eval("document.getElementById(\'" + input_id + "\').value")){
      eval("document.getElementById(\'" + input_id + "\').value = \"\"");
   }
}

var regExp = /^.+\@.+\..+$/; //Define regular expression for email address validation 

function formSub(my_id){

   if(document.getElementsByName('name')[0].value == "" || document.getElementsByName('name')[0].value == "Name"){
      alert("Please supply your name");
      return false;
   }
   
   if(!document.getElementsByName('email')[0].value.match(regExp)){ //Check email address with regular expression
      alert('The email address you have given is not valid.\nPlease supply a valid email address.');
      return false;
   }

   if(document.getElementsByName('spam')[0].value != '7' && document.getElementsByName('spam')[0].value != 'seven'){
      alert("Spam Check: (What is 4 + 3?)");
      return false;
   }
   
   eval("document.getElementById('" + my_id + "').submit();");

}