Get all List items from Subsites using ECMAScript

<script type="text/javascript" language="javascript">

     ExecuteOrDelayUntilScriptLoaded(RetrieveListItems, "sp.js");
     
     var clientContext = null;
     var spWebobj = null;
     var spListobj = null;
     var liCount;
     var items;
     var listItemInfo = '';  
     
     function RetrieveListItems() {

         clientContext = new SP.ClientContext.get_current();

         this.site = clientContext.get_web();

         this.webSubSites = site.get_webs();

         clientContext.load(this.webSubSites, 'Include(Title, ServerRelativeUrl)');

         clientContext.executeQueryAsync(Function.createDelegate(this, this.onLoadSubWebs), Function.createDelegate(this, this.onQueryFailed));

     }

     function onLoadSubWebs(sender, args) {

         items = [];              
 
         for (var x = 0; x < this.webSubSites.get_count(); x++) {        

             web = this.webSubSites.itemAt(x);
             
             var siteUrl = web.get_serverRelativeUrl();             

                 spListobj = web.get_lists().getByTitle("Tasks");

                 var spCamlQuery = new SP.CamlQuery();               

                 var spViewXML = '<View><Query><Where><And><Leq><FieldRef Name="DueDate"/><Value Type="DateTime"><Today OffsetDays="-3"/></Value></Leq><Neq><FieldRef Name="Status"/><Value Type="Text">Completed</Value></Neq></And></Where></Query></View>'; 
                 
                 spCamlQuery.set_viewXml(spViewXML);

                 var spListobjItems = spListobj.getItems(spCamlQuery);                                 

                 var itemDetails = new Object;

                 itemDetails.ListItems = spListobjItems;
                 itemDetails.WebTitle = web.get_title();
                 itemDetails.TaskListOverDueViewURL = siteUrl + '/Lists/Tasks/';

                 items.push(itemDetails);

                 clientContext.load(spListobjItems, 'Include(Id, FileDirRef)');     
                                                                                
            }

         clientContext.executeQueryAsync(Function.createDelegate(this, this.onLoadTaskDetails), Function.createDelegate(this, this.onQueryFailed));
     }

     function onLoadTaskDetails(sender, args) {

         var htmlGetTitle = "<ul>";

         var htmlGetCount = "<ul>";        
         
         for (var x = 0; x < items.length; x++) {            

                 var itemDetails = items[x];
                 
                 htmlGetCount += "<li>" + itemDetails.ListItems.get_count() + "</li>";

                 htmlGetTitle += "<li> <a href='" + itemDetails.TaskListOverDueViewURL + " ' target=_blank'> <u>" + itemDetails.WebTitle + "</u> </a> </li>";             
         }
         document.getElementById('divSiteCount').innerHTML = htmlGetCount;
         document.getElementById('divSiteTitle').innerHTML = htmlGetTitle;        
        }
 

     function onQueryFailed(sender, args) {

         alert('Request failed. ' + args.get_message() + '\n' + args.get_stackTrace());
     }

      </script>   

<table> 
     <tr>
       <th>Project</th>
       <th>Exceptions</th>
   </tr>
   <tr id="divSiteListings"> 
       <td> <div id="divSiteTitle"></div></td>     
       <td> <div id="divSiteCount"></div></td>   
   </tr> 
  </table>