// Checks that given string is valid as email address
	function checkEmail(email){
	  var filter=/^([\w-]+(?:\.[\w-]+)*)@((?:[\w-]+\.)*\w[\w-]{0,66})\.([a-z]{2,6}(?:\.[a-z]{2})?)$/i
	  if (filter.test(email)) return true;
	  else return false;
	}
	 
	var origBorder = "1px solid #7F9DB9";
	var strErrorBorder = "1px solid red";
	 
// Validate user input
	function validateUserInput() {

		   var elemName= document.getElementById("txtname");
		   var elemEmail = document.getElementById("txtemail");
		   var elemTelephone= document.getElementById("txttelephone");
		   
		   var boolError = false;
		   var strError = "";
		   
		   var vEmail = elemEmail.value;
		   var vTelephone = elemTelephone.value;
		   var vName = elemName.value;
	  
		   elemName.style.border = origBorder;
		   elemEmail.style.border = origBorder;
		   elemTelephone.style.border = origBorder;
		   
// Trim white-space
		   vName = Trim(vName);
		   vEmail = Trim(vEmail);
		   vTelephone = Trim(vTelephone);
		   
// Run validation
		   if(vName.length < 3) {
				  
				strError += "Please fill in your name\n";              
				elemName.style.border = strErrorBorder;
				boolError = true;
		   }
	 
		   if(vEmail.length > 0 && !checkEmail(vEmail)) {
				strError += "Please fill in a VALID email address\n";
				elemEmail.style.border = strErrorBorder;
				boolError = true;
		   } 
		   
		   if(vEmail.length == 0 && vTelephone.length == 0) {
				strError += "Please fill in email or telephone number\n";            
				elemEmail.style.border = strErrorBorder;
				elemTelephone.style.border = strErrorBorder;
				boolError = true;
		   }
		   
	if( boolError ) alert ( strError );
	return ! boolError;
}
 
	 
// Trim functions
	function Trim(TRIM_VALUE)
	{
		if(TRIM_VALUE.length < 1){
			return "";
		}
		TRIM_VALUE = RTrim(TRIM_VALUE);
		TRIM_VALUE = LTrim(TRIM_VALUE);
		if(TRIM_VALUE==""){
			return "";
		}
		else
		{
			return TRIM_VALUE;
		}
	}
	function RTrim(VALUE)
	{
		var w_space = String.fromCharCode(32);
		var v_length = VALUE.length;
		var strTemp = "";
		
		if(v_length < 0){
			return "";
		}
		var iTemp = v_length -1;
	 
		while(iTemp > -1){
			if(!(VALUE.charAt(iTemp) == w_space))
			{
				strTemp = VALUE.substring(0,iTemp +1);
				break;
			}
			iTemp = iTemp-1;
		}
		return strTemp;
	}
	 
	function LTrim(VALUE)
	{
		var w_space = String.fromCharCode(32);
		
		if(v_length < 1){
			return"";
		}
		var v_length = VALUE.length;
		var strTemp = "";
	 
		var iTemp = 0;
	 
		while(iTemp < v_length){
			if(VALUE.charAt(iTemp) == w_space){
			}
			else{
				strTemp = VALUE.substring(iTemp,v_length);
				break;
			}
			iTemp = iTemp + 1;
		}
		return strTemp;
	}
	
/*feedback form submission
function submitform()
{
  document.form1.submit();
}
*/

function validateFeedback() {
	if(document.getElementById("txthow_know").checked == false && document.getElementById("txtdid_buy").checked == false && document.getElementById("txthow_many").checked == false) {
		alert("This form has not been filled in.");
		return false;
	}	
}