What is the best way to tally up the occurrences of a specific class within an Angular application?

After reviewing the resources provided below on impure and pure pipes in Angular applications:

  • What is impure pipe in Angular?

I have been curious about inspecting the instances created by an Angular application firsthand, although I am uncertain if this is feasible. I'm interested not only in the pipes but also in other elements like components.

Having a better grasp of when these instances are generated with respect to the digest cycle would greatly benefit my understanding.

Are there any specialized debugging tools or profilers available for this purpose?

angulartypescriptdebuggingprofilerinstances

Answer №1

I haven't had the need to use the debugging/profiler tool, so I can't speak to its effectiveness for that purpose. However, let me provide some insight into instancing.

Components, Pipes, and Directives are instantiated for each use, meaning they each have their own lifecycle and are fully constructed individually.

Services, on the other hand, can be singletons or instanced for each use. Many of the services you create in your app are singletons, such as those that handle data retrieval from a server, manage state (store), display user information on demand (toastr), handle language translations, and more.

To delve deeper into Singleton services, I suggest reading https://angular.io/guide/singleton-services.

If you want to see how instances are being created, you can easily achieve this by adding simple logs in the constructor (which runs when a new instance of a class is created).

To log the name of the class each time it is constructed, simply include 

console.log(this.constructor.name)
in the constructor of the class you wish to track.

Answer №2

Achieving this can be accomplished by utilizing a common element that is shared across all instances of a specific class. In Angular applications, services are utilized to facilitate data sharing among components. Following the same principle:

  • Introduce a public variable in a service, such as public count: number = 0, within the file SharedService
  • Inject the service instance into the class constructor and increment the variable. constructor( private sharedServiceInstance: SharedService) { this.sharedServiceInstance.count++; }
  • Retrieve the service count variable to determine the total number of instances created post initialization of the application. console.log(this.sharedServiceInstance.count)

Answer №3

While I can't guarantee it will meet all your needs, Augury is a tool that can help with debugging Angular applications.

You can find more information about it at augury.angular.io

Personally, I have found it to be quite helpful in various situations.

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