issue on map when try to get an array from datatable rows

hi
i have an issue when try to get all data-filter in column,
i wish return an array [0,1]

but i have an object

i use this code ( this is here Datables object)

  let t = this.rows().data().map(x => x[1]['@data-filter']).unique()
  console.log(t)
  t.forEach(x => {
      select.append('<option>'+x+'</option>');
   })

because it not return clean array, it have an issue in foreach