wait for value from observable

Question

I want to get the value of an observable, and return it from a synchronous function.

If the code was in html, I could use {{singleEvents$ | async}} .

I don't know of something similar in TS.

I know it's possible to subscribe for an observable to get it's values, but this is still asynchronous. I want the next line of code to only execute after I got a (single) value from the observable, and for the flow to continue synchronously afterwards.

Thanks,

P.S The reason I want this is that Im running different flows of the code depending on the result. I'd need to make everything asynchronous otherwise.

Edit: this is how the code looks like -

function ReturnVal() {
  let obs : Observable<boolean> = getFromHttp();
  return ... unsure what to write here ...;
}

function DoStuff () {
  ... lots of logic ...
  if ReturnVal() {
     return;
  }
  ... lots of logic ...
}

Answer 1

You can use pipe operators.

ngOnInit() {
  singleEvents$.pipe(
    take(1), // this ensures only one event fires and automatically unsubscribes after code runs
    // tap(console.log) // for debugging
  ).subscribe((singleEvents: ISingleEvent[]) => {
    // do something with singleEvents
  })
}

Edit

One way to do something similar to your example

returnVal$(): Observable<boolean> {
  let obs : Observable<boolean> = getFromHttp();
  return obs
}

doStuff () {
  ... lots of logic ...

  this.returnVal$().pipe(
    take(1),
  ).subscribe(returnVal => {
     if (returnVal) {
       return;
    }
    ... lots of logic ...
  })
}