How can i call phonegap functions in html

How can i call phonegap functions in html

Im building a basic html application for mobile using jquery mobile and phonegap build. i have a button for closing the application in mobile. i got the code for closing the application. my code is
  function close_app(){ navigator.app.exitApp(); }  
I build my application with phonegap build . and tested it in my android phone but the code is not working for me. Can you tell me is it possible to use phonegap functions in build phonegap. if possible how can i do that?