how to bind drop down list box in data grid using java script

i have a one data grid that contain a drop down list box. i bind data grid and ddl when page is loaded. i have also one link button(add button) in data grid. when i click on the link button(add) the new page(child page) is open using pop up dialog box,. this child  page has one save button. when click on the save button new value added in database that relate to drop down list box and  back  to  parent page and  i want to bind drop down list boxdown list box using java script

plz help