rxjs “找到” 可观察到的对象的 hashmap

Question

Say I have class hiObject where it has variables id: number and a value: number inside. \

Then I have hiObjects$: Observable<HashMap<hiObject>> =... in an other class.

I wish to find the hiObject inside this hashmap observable where id = 2 , and assign their value to an digit$: Observable<number>

Currently I'm using this.digit$ = hiObjects$.pipe(map(hiObjects) => for(const index in hiObjects)...) , basically looping through the entire hashmap and looking for when id is equal to 2.

But I think there should be another alternate where you use rxjs find and map , wondering if anyone could help. Thank you!

EDIT : Think hashmap does not allow find, so this question is useless now..

TS:

export interface hiObject {
  id?: number;
  value?: number;
}

export class smth implements OnInit{
  public digit$: Observable<number>;
  public hiObjects$: Observable<HashMap<hiObject>> = ...
  ngOnInit() {
    this.digit$ = this.hiObjects$.pipe(
      map((collections) => {
        for (const index in collections) ...})
    );
  }
}

Answer 1

You're close, use .find and then the .value if it's actually found

this.digit$ = hiObjects$.pipe(
    // this finds the hiObject that has an id of 2, and then returns the value
    map(hiObjects => hiObjects.find(id => id === 2)?.value)
);