how to use the unsubscriptionerror function from the rxjs library in javascript

The UnsubscriptionError is a class in the RxJS library that represents an error that occurs when an unsubscription fails. It is used to provide more information about the unsubscription failure.

To use UnsubscriptionError in your JavaScript code, you need to import it from the RxJS library first:

index.tsx
import { UnsubscriptionError } from "rxjs";
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Or, if you're using a script tag to add RxJS to your page:

<script src="https://unpkg.com/rxjs/bundles/rxjs.umd.min.js"></script>
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Then, you can use the UnsubscriptionError class to catch unsubscription errors in your Observable code. Here's an example:

index.tsx
import { Observable } from "rxjs";
import { UnsubscriptionError } from "rxjs";

const observable = new Observable((observer) => {
  const intervalId = setInterval(() => {
    observer.next("tick");
  }, 1000);

  return () => {
    clearInterval(intervalId);
    throw new UnsubscriptionError();
  };
});

const subscription = observable.subscribe({
  next: console.log,
  error: console.error,
});

setTimeout(() => {
  subscription.unsubscribe();
}, 5000);
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In this example, we create a simple Observable that emits a "tick" value every second. When the subscription is unsubscribed, it throws an UnsubscriptionError.

We then subscribe to the Observable and set a timeout to unsubscribe after 5 seconds.

If the unsubscription fails, the error handler function will be called and we can use instanceof to check if the error is an UnsubscriptionError.

index.tsx
subscription.add(() => {
  if (error instanceof UnsubscriptionError) {
    console.log("Unsubscription error caught!");
  }
});
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