let defaultOptions = {
    pageLength: 10,
    dom: 'Bfrtipl',
    buttons: [
        {
          extend: 'pdfHtml5',
          orientation: 'landscape',
          exportOptions: {
              columns: ':visible(:not(:last-child)'
          }
        },
        {
          extend: 'excelHtml5',
          exportOptions: {
              columns: ':visible(:not(:last-child)'
          }
        },
        {
          extend: 'print',
          exportOptions: {
              columns: ':visible(:not(:last-child)'
          }
        }
    ],