function checkInput() {
	var error = "";

	var first_name = window.document.form.first_name.value;
	var last_name = window.document.form.last_name.value;	
	var contact = window.document.form.contact.value;
	var email = window.document.form.email.value;
	var confirm_email = window.document.form.confirm_email.value;
	var mailing_address = window.document.form.mailing_address.value;
	var postal_code = window.document.form.postal_code.value;
	
	if (first_name == "") {
		error = error + "Please fill in your first name.\n";
	}

	if (last_name == "") {
		error = error + "Please fill in your last name.\n";
	}

	if (contact == "") {
		error = error + "Please fill in your contact no.\n";
	}
	
	if (email == "") {
		error = error + "Please fill in your email.\n";
	} else if (email != confirm_email) {
		error = error + "Your email address do not tally. Please try again.\n";
	} else if (email != "" && validemail(email) == false) {
		error = error + "Your email address is invalid. Please try again.\n";	
	}

	
	if (mailing_address == "") {
		error = error + "Please fill in your mailing address.\n";
	}
	
	if (postal_code == "") {
		error = error + "Please fill in your postal code.\n";		
	} else if (!IsNumeric(postal_code)) {
		error = error + "Invalid postal code. Please try again.\n";				
	}
	
	if (error != "") {
		alert(error);
		return false;
	} else {
		return true;
	}
}

function validemail(emailAddress) {
    var re = /^(([^<>()[\]\\.,;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/
    return re.test(emailAddress);
}

function IsNumeric(sText) {
   var ValidChars = "0123456789.";
   var IsNumber=true;
   var Char;
 
   for (i = 0; i < sText.length && IsNumber == true; i++) { 
      Char = sText.charAt(i); 
      if (ValidChars.indexOf(Char) == -1) {
         IsNumber = false;
      }
   }
   return IsNumber;
}