$(document).ready(function(){
                
            
                $("#submit").attr("disabled", true); 
                $("#kwh").attr("disabled", true); 
                
                var plz_input = $("#plz");
              
                plz_input.keyup(function() {
                    if(plz_input.val().length == 5) {

                        var term = plz_input.val();

                        /* Send the data using post and put the results in a div */
                        $.post( "/Online_Service/plzcheck2.php", { plz: term },
                        function( data ) {
                            if(data == true) {
                                $("#submit").prop("disabled", false); 
                                $("#kwh").prop("disabled", false);
                            } else {
                                $('.error').empty().append("Ihre PLZ liegt nicht im Einzugsgebiet.");
                            }
                        });
                    } else {
                        $("#submit").attr("disabled", true);
                        $("#kwh").attr("disabled", true);
                        $(".error").empty();
                    }
                });
            });