Update select dropdown list on filtering js-grid d

Question

I want to update the select box list on filtering event of jsgrid. I read the documentation but there is no such feature for JsGrid.In the fiddle there is a country dropdown which has different countries. When i give input in Age as 29 it return 2 rows with country as China & Russia. So on this filtering i want to update the select box list with only China & Russia and on giving blank input or removing all the filter items it should update the dropdown with original countries list. I had searched a lot ,i didn't find any solution. Fiddle link - fiddle