function checkemail(str){
  var filter=/^.+@.+\..{2,4}$/
  return (filter.test(str))
}
function validate(that) {

   if(that["mname"].value == "") {
      alert("Please enter your name");
      return false;
   } else if(that["memail"].value.length < 1) {
        alert("Please enter a valid E-mail Address");
        return false;
   } else if(!checkemail(that["memail"].value)) {
        alert("Please enter a valid E-mail Address");
        return false;
   } else if (that["mcompany"].value == "") {
   		alert("Please enter your organisation name");
      	return false;
	} else if (that["maddress"].value == "") {
   		alert("Please enter your organisation address");
      	return false;
	} else if (that["invoice"].checked == true) {
		if (that["mcompany_invoice"].value == "") {
	   		alert("Please enter your organisation name (for invoice)");
	      	return false;
		} else if (that["maddress_invoice"].value == "") {
	   		alert("Please enter your organisation address (for invoice)");
	      	return false;
		}
	} else if (that["mphonenumber"].value == "") {
   		alert("Please enter your telephone number");
      	return false;
	} else if (that["no_members"].value == "0" && that["no_nonmembers"].value == "0") {
   		alert("Please select the number of member and non-member tickets required on this booking");
      	return false;
    } else if(!that["conditions"].checked) {
      alert("Please acknowledge that you accept the Terms & Conditions");
   	  return false;
	} else if (that["att1"].value == "") {
   		alert("Please enter name and details for attendee 1");
      	return false;
	} else if (that["att1_email"].value == "") {
   		alert("Please enter e-mail address for attendee 1");
      	return false;
     } else if(!checkemail(that["att1_email"].value)) {
        alert("Please enter a valid e-mail address for attendee 1");
        return false;		
    }	

	if (window.validateEnd) {
		return validateEnd(that)
	} else {
  	return true
	}
}

function hideLayer(whichLayer) {

	if (document.getElementById) {
	document.getElementById(whichLayer).style.display = "none";
	}
	else if (document.all) {
	document.all(whichLayer).style.display = "none";
	}
	else if (document.layers) {
	document.layers["invoiceaddress"].document.layers[whichLayer].display = "none";
	}

}

function showLayer(whichLayer) {

	if (document.getElementById) {
	document.getElementById(whichLayer).style.display = "block";
	}
	else if (document.all) {
	document.all(whichLayer).style.display = "block";
	}
	else if (document.layers) {
	document.layers[whichLayer].display = "block";
	}
}

function handleClick(that) {
if (that.checked == true) {
	showLayer("invoiceaddress");
} else {
	hideLayer("invoiceaddress");
}
}