How do I prefetch url's in ionic/angularjs?

Question

I am pretty new to ionic 1 and I am working on an application (with Ionic 1 and angular js) with multiple URLs where each URL brings up a list of categories, followed by a list

Answer 1

Best way to share data between different views in angular is to use a service as it is a singleton and can be used in other controllers. In your main controller you can prefetch your lists of categories asynchronously through a service which can be shared for next views.Below is a small demo which you refer

angular.module("test").service("testservice",function('$http',$q){
    var lists = undefined;
    // fetch all lists in deferred technique
    this.getLists = function() {
      // if lists object is not defined then start the new process for fetch it
      if (!lists) {
        // create deferred object using $q
        var deferred = $q.defer();
         // get lists form backend
        $http.get(URL)
          .then(function(result) {
            // save fetched posts to the local variable
            lists = result.data;
            // resolve the deferred
            deferred.resolve(lists);
          }, function(error) {
            //handle error
            deferred.reject(error);
          });
        // set the posts object to be a promise until result comeback
        lists = deferred.promise;
      }

      // in any way wrap the lists object with $q.when which means:
      // local posts object could be:
      // a promise
      // a real lists data
      // both cases will be handled as promise because $q.when on real data will resolve it immediately
      return $q.when(lists);
    };
this.getLists2=function(){
//do it similarly as above
};
}).controller("mainController",function(testservice,$scope){
    $scope.lists1=testervice.getLists()
        .then(function(lists) {
        //do something 
        });
    };
    $scope.lists2=testervice.getLists2()
        .then(function(lists) {
        //do something 
        });
    };
    $scope.lists1();
    $scope.lists2();
}).controller("demoController1",function(testservice,$scope){
    $scope.lists1=testervice.getLists()
        .then(function(lists) {
        //do something 
        });
    };
    $scope.lists2=testervice.getLists2()
        .then(function(lists) {
        //do something 
        });
    };
    $scope.lists1();
    $scope.lists2();
});