How to pass a promise as a parameter

Question

I want to pass a promise as a parameter to another function, use it as a callback. The code I have works as follows

Component 1
function1() {
    let promise: Promise<any>;
    this.function2(promise);
    promise.then(response => console.log(response));
}

Component 2
function2(promise) {
    // Some Code 
    this.dialog.afterClosed().subscribe(data => {
       promise.resolve(data);
    });
}

Doing it this way produces an error in function 1, the error is: Cannot read property 'then' of undefined

Answer 1

Maybe what you want to do is something like:

function1() {
  const promise: Promise = new Promise((resolve, reject) => {
    this.function2(resolve);
  });

  promise.then(response => console.log(response));
}

function2(resolveFn: any) {
    // Some Code 
    this.dialog.afterClosed().subscribe(data => {
       resolveFn(data);
    });
}

[UPDATE]: IMO, you should be doing it entirely with observables (no need for promises here):

function1() {
  const afterClosed$: Observable<any> = this.function2();
  afterClosed$.subscribe((response: any) => console.log(response));
}

function2(): Observable<any> {
  // Some Code 
  return this.dialog.afterClosed();
}