javascript - Best way to 'return true' based on conditions from nested functions -

this may novice question trying create function returns true. however, based on happens within several other functions inside.

function checkgeo(){      // check geolocation     if( "geolocation" in navigator ) {          navigator.geolocation.getcurrentposition( function(position){             sessionstorage.pinlat = position.coords.latitude;              sessionstorage.pinlon = position.coords.longitude;              // position object set!         });          // position not defined         if ( position.coords.latitude && position.coords.longitude ){             return true;          }      }  } 

this order want things happen geolocation check i'm bit surprised nested if tested before getcurrentposition method finishes.

putting condition within getcurrentposition success function , returning true there not make checkgeo return true. how check if asyncronous function has ended , therefore check results in order return true?

have function have finished variable

function checkgeo(){     var self = this;     this.ready  = function () {}     this.result = false;     if("geolocation" in navigator) {         navigator.geolocation.getcurrentposition(function(position) {             sessionstorage.pinlat = position.coords.latitude;              sessionstorage.pinlon = position.coords.longitude;              self.result = (position.coords.latitude && position.coords.longitude);             self.ready.call(self);         });     } } 

now can use function:

var run = new checkgeo(); run.ready = function () {     alert(this.result); //both work     alert(run.result);  //both work }; 

a bit more complicated, better programming in opinion.