Jqery remote validation example

<script>
$(function(){
 $("#register_form").validate({
rules: {
username:{
required: true,
},
email:{
required: true,
email: true,
"remote":
                    {
                      url: "<?=base_url()?>Register/check_email",
                      type: "post",
                      data:
                      {
                          email: function()
                          {
 return $('#register_form :input[name="email"]').val();
                          }
                      }
                    }
//remote: "<?=base_url()?>Register/check_email"
},
mobile:{
required: true,
    minlength:9,
    maxlength:10,
},
password:{
required: true,
},
cnfpassword:{
equalTo: "#password"
},
agree:{
required: true,
}
},messages:{
agree:{
required:'',
},
email:{
remote : jQuery.validator.format("{0} is already taken.")
}
},submitHandler: function(form) { form.submit(); }
});

});
</script>

PHP script

< ?php /* check if email is already registered */ 

//connect to db using mysqli 

if (!empty($_POST['email'])) { 

       $email = $mysqli->real_escape_string($_POST['email']); 

       $query = "SELECT ID FROM users WHERE user_email = '{$email}' LIMIT 1;"; 

       $results = $mysqli->query($query); 

       if($results->num_rows == 0) { 

              echo "true"; //good to register 

      } else { 

             echo "false"; //already registered 

      } 

} 

else { echo "false"; //invalid post var }

 ?>