Factories & Services in AngularJS

Hi Li

Services are basically specific functionality that is encapsulated. Think of it like a function that holds specific functionality that you call whenever you want to execute that functionality anywhere in your program. Instead of just declaring, adding logic and invoking the function it works in a different way in Angular. You need to create the service by using either app.factory or app.service, and then add the functionality:

app.service('myService', function(){

//your service logic here  

});

When you want to use the service in your Angular app you need to used dependency injection and add a reference to your service in your controller and then you can invoke the functionality within your controller:

app.controller('myController', [$scope, myService, function($scope, myService){

$scope.myFunction = myService.customLogic();

}]);

The main reasons for removing the logic from the controller is to make your services reusable and available to other controllers. Also, it helps to make your code more readable and clean. Besides creating your own services you can use the builtin ones that Angular provides such as the $http service that lets you get data from external APIs, to use this you have to use dependency injection just like you did for your custom service/factory.