Subscribe method, an Observable in RXJS

Here’s an example:

const myObservable = of(1.2.3);

        // Create an Observer object -Observer(handle next, error, complete callback)
        const myObserver = {
         next: x= > console.log('Observer got a next value: ' + x),
        error: err= > console.error('Observer got an error: ' + err),
        complete: () = > console.log('Observer got a complete notification'),};Observables subscribe to Observable messages via the Subscribe function of Observable
        myObservable.subscribe(myObserver);
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Subscribe (Observable), passing in an observer containing the callback:

The last two parameters are undefined:

In the toSubscriber function, because nextOrObserver is the object I passed in manually, the first two IF conditions are not met:

Go to the default implementation and create a Subscriber object:

Subscriber is a subclass of Subscription:

In our current Subscriber constructor, create an instance of SafeSubscruber: this is passed in as parent Subscriber

EmptyObserver is imported from./Observer:

As you can see from SafeSubscriber’s implementation, the next, error, and complete function names passed in to the Observer are hard-coded and must conform to this naming convention:

The object.create () method creates a new Object, using an existing Object to provide the __proto__ of the newly created Object.

Perform the subscribe:

Sink’s destination contains the complete, next, error logic passed in by the application:

As you can see, the logic of subscribe is to loop through all Observable parameters, call observer next, and then call complete:

Next calls the private _next method:

Enclosing _next calls this. Destination. Next:

The final call to the next method passed in by the application programmer:

Final output:

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