top scroller for data table

nginx/covid_website/assets/js/map.js

@@ -307,9 +307,20 @@ function populateDataTable(geojsonData, tableDivID) {
   } );
 
   var table = $('#'+tableDivID).DataTable({
-    "scrollX": true
+    "scrollX": true,
+    scroller: true
   }   
   );
+
+  // Put top scroller
+  $('.dataTables_scrollHead').css({
+    'overflow-x':'scroll'
+  }).on('scroll', function(e){
+    var scrollBody = $(this).parent().find('.dataTables_scrollBody').get(0);
+    scrollBody.scrollLeft = this.scrollLeft;
+    $(scrollBody).trigger('scroll');
+  });
+
   $('.dataTables_length').addClass('bs-select');
 
     // Apply the search