function iterateSheets()
{
  var ss=SpreadsheetApp.getActive();
  var sh=ss.getSheetByName('filesSheet');
  sh.clear();
  var folder=DriveApp.getFolderById('1axTLHOBPhl5_u7ngFOxViHg14OSw7pVC');//replace id with actual id of folder
  var files=folder.getFilesByType(MimeType.GOOGLE_SHEETS);
  var consol_sheet = SpreadsheetApp.openById('18JnkQYa1L-FhXFmKJBrqJ6GI7BBO-V8QAVKP8PLLoXo').getActiveSheet();
  var x=2;
  var z=0;
  var final_values = new Array(50000);

while(files.hasNext())
 {
   var file=files.next();
    var ts=SpreadsheetApp.openById(file.getId());
    var allShts=ts.getSheets();

       for(var i=0;i<3;i++)   //allShts.length
       {
            var consol_values = allShts[i].getRange(8,1,40,26).getValues();  //.getRange(8, 1, 1, 1).getValues();
            var headers = allShts[i].getRange(7,6,1,20).getValues();  //.getRange(8, 1, 1, 1).getValues();
            var position= allShts[i].getRange("B1").getValue();
            var period = allShts[i].getRange("B2").getValue();
            var email = allShts[i].getRange("B3").getValue();

         for (var z = 0;z<20;z++)//
         {

           for (var y= 0;y<40;y++)
           {
               if (consol_values[y][i] != "")
               {
              /*  consol_sheet.getRange(x,1).setValue(consol_values[y][0]);  //AI pack
                consol_sheet.getRange(x,3).setValue(consol_values[y][1]); //measure
                consol_sheet.getRange(x,4).setValue(email);
                consol_sheet.getRange(x,5).setValue(position);


                final_values[x] = [];
                final_values[x][0]  =consol_values[y][0];  //AI pack
                 //blank
                final_values[x][2]  =(consol_values[y][1]); //measure
                final_values[x][3]  =(email);
                final_values[x][4]  =(position);
                final_values[x][5]  =(headers[0][z]);//location
                final_values[x][6]  =1;
                final_values[x][7]  =(period);
                final_values[x][8]  =(consol_values[y][3]); //price
                final_values[x][9]  =(consol_values[y][z+5]); //fcst

                if (consol_values[y][z+5] != "")
                {
                    final_values[x][10] =(consol_values[y][25]); //fcst value
                }


                x = Number(x)+1  //row count for consolidation output

              }
          }
         }
      }
    }


consol_sheet.getRange(2,1,x,10).setValues(final_values);

 }

[
  [1,,'orange'], // 2nd element of this inner array is empty
  , // 2nd element of the outer array is empty
  [] // This array is empty
]

[
  [1,'','orange'],
  ['','',''],
  ['','','']
]

consol_sheet.getRange(2,1,final_values.length,final_values[0].length).setValues(final_values);