I want this feature in Veronika Theme, kindly give me a solution..
Once a state is selected then the cities dropdown is populated with all cities for the chosen state. the first box is blank for typing in a name. As that name is typed the comparable cities are underlined. As more letters are typed, the list is auto shortened to only those cities that have the exact same letters Look closely at included screenshot.
First, all cities in Michigan show in dropdown. when the "a" was typed, all cities with an "a" stayed. All others disappear. Same when the next letter was typed which was a "c". Now all cities with "ac" are left. The rest disappear. Notice the underline for the 2 letters so far used under each remaining city.
Using a system like this gives the visitor 2 options. One is to chose from the dropdown. The other is to type in their own choice. User can stop typing at any type and chose from the remaining cities. If no city by the typed name is available then no city name will be left in the dropdown.