RxJS create new Observable "Array" from and static array in typescript

Question

I am able to create observable from an array but its type is Observable<number> not Observable<number[]>

getUsers(ids: string[]): Observable<number[]> {
   const arraySource = Observable.from([1, 2, 3, 4, 5]);
   //output: 1,2,3,4,5
   const subscribe = arraySource.subscribe(val => console.log(val));

   let returnObserable = Observable.from([1, 2, 3, 4, 5]);
   return returnObserable; //error at this line, because of the return type
}

Is there any other way to create observable other than from ?

martin · Accepted Answer · 2018-02-07 10:59:03Z

5

If you want the entire array to be emitted as a single emissions use Observable.of instead:

const arraySource = Observable.of([1, 2, 3, 4, 5]);

Observable.from iterates the array and emits each item separately while Observable.of takes it as without any further logic.

Alternatively, you could also nest two arrays but that's probably too confusing:

const arraySource = Observable.from([[1, 2, 3, 4, 5]]);

edited Feb 7, 2018 at 10:59

answered Feb 7, 2018 at 10:55

martin

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3 Comments

Sreekumar P Over a year ago

Observable.of([1, 2, 3, 4, 5]) this worked, then what is the use of Observable.of([[1, 2, 3, 4, 5]]) ?

martin Over a year ago

Sorry, my bad! I wanted to write Observable.from([[1, 2, 3, 4, 5]])

user1608841 Over a year ago

@martin .. sorry for late comment..had one doubt...when using .of([1, 2, 3, 4, 5]) and binding to HTML using async pipe works well. However using .from([1, 2, 3, 4, 5]) and binding with async pipe gives an error .. I am wondering why so ?

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