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angularjsdesign-patternssingleton
Deepankar Bajpeyi
Deepankar Bajpeyi

Reputation: 5889

Why are angular services Singletons?

I am trying to understand singleton pattern.

I write a lot of code in angular and recently I wanted to refactor some of my code and move it to a common place which can be shared by different controllers.So I moved all common utils to my services.

Now the documentation over here says that angular services are singletons but I want to understand the reason behind having singleton pattern here ? Why not have multiple instances of the service object instead of passing references to controllers ?

Upvotes: 2

Views: 307

Answers (2)

Christina
Christina

Reputation: 3732

Angular services are the recommended way to exchange data and communicate between controllers. In order therefore to allow this data exchange, services are singleton objects which means that you are guaranteed to have the same service reference between all your controllers.

As an example, imagine that you have an Angular application that displays a list of messages received from another user in the center of the page, as well as the number of received messages or new message notifications in the header. The header and the page content will most probably be under different scopes and be handled by different controllers. In order for these two controllers to have the same view of messages received and be able to display them consistently they will need to use a singleton object holding this information. This object is an Angular service.

Upvotes: 2

manasi sakhare
manasi sakhare

Reputation: 1051

It all falls in the name "Service". Service, acts like a medium to communicate between controllers or even directives for that matter. Not only for communication, you can add a set of utility functions in your service, which can be used throughout the module/app. This does not need to have multiple instances to serve the purpose. Hence, singleton.

Upvotes: 5

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