How I did my first polling

I’ve been working as a frontend developer at hibob for 2 years now and truly enjoy working on such a complex product.

I was recently tasked with creating a benefits product in our system, and want to share with you how I ended up doing this in bob.

To start, I needed to create a polling mechanism. The timer for that polling was controlled by the server, and the client was responsible for handling the response and triggering the correct event according to the response.

I decided to use observables streams.

Each response will trigger the next event/error in case something wrong happened in the process.

Let’s see some code :)
First I have created a stream of `status` that will trigger a promise function awaiting our server.

status$: Subject<PollingStatusEvent> = new Subject()
interface PollingStatusEvent {
  status: string;
  description: string;
}
// Now let's define the number of time the client will try to receive an answer: 
const INTERVAL_RETRIES = 12;
And at last an enum to indicate Success or still in progress. Convention that agreed with the server.
enum PollStatus {
  success = 'Success',
  inProgress= 'InProgress'
}

In addition success function `ourSuccessFunction` And error function `errorHandler`

public statusProvider(id: string): void {
  this.status$
    .pipe(take(INTERVAL_RETRIES))
    .subscribe(
      () => {
        this.apiService.status(id)
          .then((status) => {
            switch (status) {
              case PollStatus.success:
                this.ourSuccessFunction(); // triggring success  
                break;
              case PollStatus.inProgress:
                this.status$.next(status); // triggring new event
                break;
            }
          })
          .catch(error => this.errorHandler(error, errorState));
      },
      error => this.errorHandler(error, errorState),
      () => this.completeFunction()
    );
  this.status$.next(); // init the first event
}

After we are all done don’t forget to unsubscribe from our observable.

And that’s it my first polling, hope you enjoy :)