//valid email
function checkEmail (strng, msg) {
	var error = ""
	var filter  = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
	if (!(filter.test(strng))) {
		error = msg;
	}
	return error;
}

//valid number and length
function isNumber(field, reqLength, msg, msg2) {
	var error = "";
	  if (isNaN(field.value)) {
		  error = msg;
	  } else if (field.value.length < reqLength) {
		  error = msg2;
	  }
	return error;	  
}

// non-empty textbox
function isEmpty(field, msg) {
	var error = "";
	  if (field.value.length == 0) {
		 error = msg;
	  }
	return error;	  
}

// valid selector from dropdown list
function checkDropdown(choice, msg) {
var error = "";
    if (choice == 0) {
    	error = msg;
    }    
return error;
}