Display an error message with Ajax

 <?php //Display php errors error_reporting(E_ALL); // Don't forget to include your database connection file require_once 'cnxBdd.php'; //proper retrieval of variables $users = isset($ban['1']) ? trim(addslashes($ban['1'])) : NULL; $result = array(); //Initialization of the output variable if($users){ $sql = 'SELECT * FROM users WHERE username = :username'; $datas = array(':username' => stripslashes($users)); try{ $infoUsersReq = $db->prepare($sql); $infoUsersReq->execute($datas); $infoUsers = $infoUsersReq->fetch(); }catch(Exception $e){ //in case of error in the query $result['error'] = $e->getMessage(); } if($infoUsers){ if($username != $infoUsers['username']) { if($infoUsers['grade'] != 'administrateur') { if($infoUsers['chatban'] == '0'){ $banUsersChatReq = $db->prepare('...'); $banUsersChatReq->execute(array(...)); // HERE WE CHANGE THE STATUS OF THE MEMBER TO BAN HIM } else { $result['message'] = "The member is already banned!"; } } else{ $result['message'] = "You cannot ban an administrator!"; } } else{ $result['message'] = "You cannot ban yourself!"; } } else { $result['message'] = "The member does not exist!"; } } //Convert to JSON for use in javascript echo json_encode($result); 

 function ban(user){ // data to be sent to the ajax php script var data = {user:user}; //ajax call $.ajax({ type: "POST", url: urlAjx, data: data, async: async, dataType: "json", success: function(reponse){ // response is a json object containing the info returned by the php page console.log(reponse); //display the result in the browser console. var error = (typeof(reponse.error) !='undefined' && reponse.error!=null) ? reponse.error : null; if(error){ alert("Error executing the query! " + error); } var message = (typeof(reponse.message) !='undefined' && reponse.message!=null) ? reponse.message : null; if(message){ alert(message); } }, error:function(jqXHR, textStatus){ alert('error'); console.log(jqXHR); //display in the browser console } }); }