What you need is the .ajaxSend() listener. It will populate a global event listener for every Ajax call - like your getJSON.
$(document).ajaxSend(function () { $.mobile.loading("show") }).ajaxStop(function () { $.mobile.loading("hide") });

What you need is the `.ajaxSend()` listener. It will populate a global event listener for every Ajax call - like your getJSON. Reference here http://api.jquery.com/ajaxSend/
$(document).ajaxSend(function () { showSpinner(); }).ajaxStop(function () { hideSpinner(); });