Ajax function with a callback

Question

I have Ajax function with a callback which fetches all the Patient data however I have some perfomance issues and trying to figure out what it might be, does anyone have idea? That's my Code

var patient = new Array();
function sync(arg, callback){   //ajax result 
    $('.loader').show();
    $.ajax({ 
        method: 'GET',
        url: 'sync/active.php',
        dataType: 'json',
        data: arg, // argument schicken und aktualisieren
        success: function(data, status, xhr){
         $('.loader').hide();    
         callback(data);
        // setTimeout(sync, ajaxDelay);
        },
        error: function(xhr, ajaxOptions, thrownError){
            console.log(thrownError);
        }
   });   
}
function onPatientCallback(data) {
        var res = data; 
        for(var i=0; i<res.length;i++){
            for(var key in res[i]){
                var value = res[i][key];
                switch(key){
                    case "id":
                        res[i][key] = parseInt(value);
                        break;
                    case "kundennr":
                        res[i][key] = parseInt(value);  
                        break;
                    case "client":
                        res[i][key] = value;
                        break;
                    case "start":
                        res[i][key] = new Date(value);
                        break;
                    case "end":
                        res[i][key] = new Date(value);
                        break;
                    case "title":
                        res[i][key] = value;
                        break;
                    case "description":
                        res[i][key] = value;
                        break;

                    case "termart":
                        res[i][key] = parseInt(value);
                        break;

                    case "userId":
                        res[i][key] = parseInt(value);
                        break;

                    default:
                        console.log("unbekannter Datentyp "+key);
                }
            }
        }
        patient = res;

}

I use the function to fill the patient variable and call it in another js file like that sync({calling: "patient"}, onPatientCallback);

Answer 1

From a short review;

• patient is a global variable, global variables are bad
• var patient = [] is more idiomatic than var patient = new Array();
• Comments should be all German or all English (I would go for all English, its the common language of the developers)

• You can group switch labels, this is valid JavaScript:

          switch(key){
              case "id":
              case "kundennr":
              case "termart":
              case "userId":
                  res[i][key] = parseInt(value);
                  break;
              case "client":
              case "title":
              case "description":
                  res[i][key] = value;
                  break;
              case "start":
              case "end":
                  res[i][key] = new Date(value);
                  break;
              default:
                  console.log("unbekannter Datentyp " + key);
  

• Your data fields should be either all English or all German (you have userId, but also kundennr), here as well I would go for all English
• Since value already contains res[i][key] for "client", "title", etc., you should probably comment on that
• Since this is real, you should not log to console for an unknown data type, you should call a REST service that will log this entry in a database table, and even possibly send out an email to developers
• var key in Object.keys(res[i]) is safer than var key in res[i], you never know when someone decides to extend Object
• Your indenting is off, consider using a beautifier