What is the difference between angular.Module.factory and angular.Module.service when creating a service?

Question

I'm getting re-acquainted with angular after a long time away, and (so far) I've discovered two ways to create an angular service. The simplest being this:

var app = angular.Module("SomeApp", [])
 .factory("SomeService", function ($log) {
 $log.info("Yea beh beh! Dis hea is a service!")
 });

This form of creating a service in angular is documented in angular.Module.factory. But, you can also see, that on the same page there is another way to create a service, using angular.Module.service.

Reading the two descriptions, I am unable to understand the differences other than .service needs you to explicitly use new to instantiate a service, whereas .factory implicitly does it for you. I might be wrong here, since I'm unable to understand because I have no clue what a $get property is. So, to wrap up:

• What is a $get property?
• What is the difference between .service and .factory?

Lastly, because this bugs me:

• With all angular.Module.{service, factory, controller}, the second argument is a function. But, for instance, you have put in a list for the second argument in a controller, and name its dependencies. Then why is the type taken to be a function, rather than object? I mean you won't know from the documentation that you can declare dependencies in a list unless you've done a tutorial or something.

• Klaster_1 Нет войне: possible duplicate of Angular.js: service vs provider vs factory?

Answer 1

Both angular.Module.factory and angular.Module.service are proxies to angular.Module.provide. When you give a function to angular.Module.factory angular creates the respective service by invoking the function and using its return value as the service. On the other hand, when you give a function to angular.Module.service angular will treat it as an constructor and invoke it with the new keyword to create the service.

Thus creating a service with angular.Module.factory looks like this:

app.factory('MySimpleService', function () {
 return {
 aServiceProperty : 'a property containing a string'
 };
});

And creating a similar service with angular.Module.service looks like this:

app.service('MyOtherSimpleService', function () {
 this.aServiceProperty = 'a property containing a string';
});

• Nafiul Islam: In what contexts would you use one over the other. To me, it feels as though I would almost always use .factory over .service.
• Spencer Alger: Generally, I use .factory to creat a constructor (by returning a function) and .service to create singleton objects (by writing properties and methods to this, or returning an instance of a constructor)
• Nikolas: I don't see any particular advantage of the one over the other. I think it's more a convention you should define in your team. I often use them as @SpencerAlger suggests.

Answer 2

1. The definition of the $get propery can be found here
2. Looks like this question has already been asked and answered. I am unable to comment, so I posted an answer.