How to avoid asynchronous processing in angular js - angularjs

Question

I'm new in angular js . I want to do authentication . I've to direct to some pages only after checking authentication. I've checkLogin function for that. While calling that checkLogin function it take some processing time. If true it redirects corresponding page. If false it remains the same page. But while calling the checkLogin function the same time it process the app.config function concurrently. I need to to block it. I've to process that only after chcklogin.
var app = angular.module('myApp', ['ngRoute', 'ngResource','ngCsv', 'ui', 'ngSanitize', 'ngQuickDate', 'ui.tree', 'blueimp.fileupload','mentio']);
app.config(function($routeProvider) {
$routeProvider
.when('/', {
templateUrl: 'app/views/login.html',
controller: 'LoginController',
title: 'Login'
}).when('/signup', {
templateUrl: 'app/views/signup.html',
controller: 'SignUpController',
title: 'Sign Up'
}).when('/dashboard', {
templateUrl: 'app/views/dashboard.html',
controller: 'DashboardController',
title: 'Dashboard'});});
app.run(function($rootScope, $location, DataService) {
var unAuthenticatedPages = ["/", "/signup"];
var checkLogin = function() {
if (!$rootScope.isLoggedIn && unAuthenticatedPages.indexOf($location.path()) === -1) {
$location.path('/');
}
};
$rootScope.isLoggedIn = true;
DataService.getUserListById(1, function(user) {
$rootScope.user = user;
});
$rootScope.$on('$locationChangeStart', checkLogin);});

Answer 1

angularjs comes with a built in promise library $q which can be injected and used something like this:
var doSomething = function() {
var deferred = $q.defer();
//do someething here, when you're ready resolve the deferred object
deferred.resolve();
//this won't execute until deferred is resolved or rejected
return deferred.promise;
};
You can also return variables with your promise if required. You can then
doSomething().then(function() {
//this executes if the promise is resolved
}, function() {
//this executes if the promise is rejected
});