housewm,
 

 ... вариант валидации формы на jquery ... 
<!DOCTYPE HTML>
<html>
<head>
  <title>Untitled</title>
  <meta charset="utf-8">
  <script src="http://code.jquery.com/jquery-1.9.1.js"></script>
  <script>
  $(function () {
         $('#foo').submit(function () {
             var $input = $('input:text', this),
                 error = '';
             $input.each(function (indx, element) {
                 $val = element.value;
                 $(element).css({
                     background: $val ? '' : (error += 'незаполнено ' + element.placeholder + '\n', '#FF9494')
                 })
             });
             if (error) {
                 alert(error);
                 return false
             }
             return true;
         });
     })
  </script>
</head>
<body>
   <form id="foo" action="\">
	<input type="hidden" name="discount" value="35%">
	<input type="text" name="name" placeholder="Имя">
	<input type="text" name="email" placeholder="Email">
	<input type="text" name="phone" placeholder="Телефон">
	<input type="submit" value="Заказать звонок">
</form>
</body>
</html>