What are the differences between a Service
, Provider
and Factory
in AngularJS?
AngularJS: Service vs provider vs factory
angularjsangularjs-factoryangularjs-providerangularjs-servicedependency-injection
angularjsangularjs-factoryangularjs-providerangularjs-servicedependency-injection
What are the differences between a Service
, Provider
and Factory
in AngularJS?
Best Answer
From the AngularJS mailing list I got an amazing thread that explains service vs factory vs provider and their injection usage. Compiling the answers:
Services
Syntax:
module.service( 'serviceName', function );
Result: When declaring serviceName as an injectable argument you will be provided with an instance of the function. In other words
new FunctionYouPassedToService()
.Factories
Syntax:
module.factory( 'factoryName', function );
Result: When declaring factoryName as an injectable argument you will be provided with the value that is returned by invoking the function reference passed to module.factory.
Providers
Syntax:
module.provider( 'providerName', function );
Result: When declaring providerName as an injectable argument you will be provided with
(new ProviderFunction()).$get()
. The constructor function is instantiated before the $get method is called -ProviderFunction
is the function reference passed to module.provider.Providers have the advantage that they can be configured during the module configuration phase.
See here for the provided code.
Here's a great further explanation by Misko:
In this case the injector simply returns the value as is. But what if you want to compute the value? Then use a factory
So
factory
is a function which is responsible for creating the value. Notice that the factory function can ask for other dependencies.But what if you want to be more OO and have a class called Greeter?
Then to instantiate you would have to write
Then we could ask for 'greeter' in controller like this
But that is way too wordy. A shorter way to write this would be
provider.service('greeter', Greeter);
But what if we wanted to configure the
Greeter
class before the injection? Then we could writeThen we can do this:
As a side note,
service
,factory
, andvalue
are all derived from provider.