How to add code behind to SandBox solution



I have a strange issue with clientcontext
The code fails on a row spListobjItems.get_count(); in onSuccess2() 
with this error:
The collection has not been initialized. It has not been requested or the request has not been executed. It may need to be explicitly requested.

Here is my code:


function onSuccess2() {
    var liCount = spListobjItems.get_count();
    for (x = 0; x < liCount; x++) {
        var listItem = spListobjItems.itemAt(x);
        var videoTitle = listItem.get_item("Title");
        }
}

    function onFail(sender, args) {
    }


var clientContext;
    var spWebobj;
    var spListobj;
    var spCamlQuery;
    var spViewXML;
    var spListobjItems;
    var imgSrc;
    var listTitle;

    function myCallback() {
       
        $("img").each(function () {
            imgSrc = $(this).attr('src');
            listTitle = imgSrc.split('/')[1];
            try {
                clientContext = SP.ClientContext.get_current();
                spWebobj = clientContext.get_web();
                spListobj = spWebobj.get_lists().getByTitle(listTitle);
                
                spCamlQuery = new SP.CamlQuery();
                spViewXML = '<View><Query><Where><Eq><FieldRef Name="FileRef"/><Value Type="Url">' + imgSrc + '</Value></Eq></Where></Query></View>';
                spCamlQuery.set_viewXml(spViewXML);
                spListobjItems = spListobj.getItems(spCamlQuery);
                clientContext.load(spWebobj);
                clientContext.load(spListobjItems);

                clientContext.executeQueryAsync(onSuccess2, onFail);
              
            }
            catch (exception) {
                return true;
            }
        });
        return true;
    }

    $(document).ready(function () {
         ExecuteOrDelayUntilScriptLoaded(myCallback, "SP.js");
       
    });