The need of making a Selection Field as Searchable was to make it more user friendly.
As a selection field can contain a lot of values and it could take a lot of time to find the desired value. So instead of scrolling we can make the whole selection field as searchable so that to find a specific record we can just type the name and the selection field will automatically highlight the most relevant value.
and add them in the “js” folder present in the Includes folder as shown below
Next you will have to include these two files in the asp page or the .inc (includes) page as shown below
Following the above steps will allow you to make the selection field as searchable.
Thus now when you search a record say “nis” the selection field automatically highlights the record “nissim aanand”.shown below