combineAll

signature: combineAll(project: function): Observable

When source observable completes use combineLatest with collected observables.

Ultimate RxJS

Examples

( example tests )

Example 1: Mapping to inner interval observable

( StackBlitz )

import { take, map, combineAll } from 'rxjs/operators';
import { interval } from 'rxjs';
// emit every 1s, take 2
const source$ = interval(1000).pipe(take(2));
// map each emitted value from source to interval observable that takes 5 values
const example$ = source$.pipe(
map(val =>
interval(1000).pipe(
map(i => `Result (${val}): ${i}`),
take(5)
)
)
);
/*
2 values from source will map to 2 (inner) interval observables that emit every 1s.
combineAll uses combineLatest strategy, emitting the last value from each
whenever either observable emits a value
*/
example$
.pipe(combineAll())
/*
output:
["Result (0): 0", "Result (1): 0"]
["Result (0): 1", "Result (1): 0"]
["Result (0): 1", "Result (1): 1"]
["Result (0): 2", "Result (1): 1"]
["Result (0): 2", "Result (1): 2"]
["Result (0): 3", "Result (1): 2"]
["Result (0): 3", "Result (1): 3"]
["Result (0): 4", "Result (1): 3"]
["Result (0): 4", "Result (1): 4"]
*/
.subscribe(console.log);

Additional Resources

📁 Source Code: https://github.com/ReactiveX/rxjs/blob/master/src/internal/operators/combineAll.ts