function validate_user_login() {
	if(!trim(document.login.user_name.value)) {
		alert('Username is empty');
	} else if(!trim(document.login.user_password.value)) {
		alert('Password is empty');
	} else {
		document.login.submit();
	}
}
function trim(jstr) { 
  var p1 = /^\s+/gi; 
  var p2 = /\s+$/gi 
   
  jstr = jstr.replace(p1,''); 
  jstr = jstr.replace(p2,''); 
  return jstr; 
}