如何使用jQuery或JavaScript将3个最近的位置返回到用户位置

In my mobile app, I've got users geolocation using the following code. I also have a geolocaion (latitude, longitude) of nearby cities. I can put the geolocation data of cities in array or SQLite database. How do I get and display the 3 closest cities near the users location using jQuery or JavaScript. I'm not using Google Maps.In my mobile app, I've got users geolocation us