What is the best way to clear an array of messages using .subscribe in JavaScript?

Within my messages.component.ts file, I have the following code snippet:

constructor(public messagesService: MessagesService) {
    this.subscription = this.messagesService.getMessage().subscribe(message => { this.messages.push(message); });
    this.subscription = this.messagesService.clearMessages().subscribe(this.messages = []);
}

The clearMessages method in my codebase looks like this:

clearMessages(): void {
    this.subject.next();
}

I'm encountering an issue with combining this code with .subscribe(), as subscribe() is not recognized with type void. How can this be resolved?

Answer №1

Considering the lack of specific details, I'm going to assume that the getMessage() function is structured like this:

getMessage(): Observable<any> {
  this.subject.asObservable();
}

In this scenario, you could emit a boolean value of false within the clearMessages() function.

clearMessages() {
  this.subject.next(false);
}

Since it doesn't return an observable, you won't be able to subscribe to it. However, the subscription is unnecessary as it is already subscribed to the getMessage() function. At this point, you can verify if the notification is valid before adding it to the array.

constructor(public messagesService: MessagesService) {
  this.subscription = this.messagesService.getMessage().subscribe(message => {
    if (!!message) this.messages.push(message); // <-- only add valid `message`
    else this.messages = []; // <-- reset to empty array if `message` is undefined
  });
}

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