Expanding Search Function on Website

A new java/javascript website that has members across America, needs to have its search function which is now just by city to find other members, changed to have a radius search function so members can find other members in surrounding cities. For example, now members search for members in New York, but the site needs to have option to extend the search to New York and a radius of either 10/20/50 miles around the city. The site is built in Java and javascript and prefer to keep the program the same if possible. Also need to add Canada and European countries to the database so members can join from all around the world and just not USA. If you need additional information, please let us know.