I was wondering if it's possible to operate, e.g. filtering, on a stream of arrays and then emit the arrays again without concatenating the elements of the arrays or using regular array operators. Let's say that I have an observable containing a single array. Then I can do the following:
const MINWEIGHT = 15;
interface fruit {
name: string;
weight: number;
}
let apple: fruit = { name: "apple", weight: 2 };
let orange: fruit = { name: "orange", weight: 20 };
let fruitBasket1 = [apple, orange, orange];
let fruitBasket2 = [apple, apple, apple];
let sub = new Subject<fruit[]>();
sub
.asObservable()
.pipe(
concatMap(x => x),
filter(x => x.weight > MINWEIGHT),
toArray()
)
.subscribe(console.log); // result: [ orange, orange];
sub.next(fruitBasket1);
sub.complete();
What if sub.complete() is not called and there are multiple emissions of fruit[] (e.g. fruitBasket2). Can the observable emit two arrays ([orange, orange], [orange]) without using regular array operators? It's easy to do with map(RxJS) -> filter(array operator), but I will like to know if it's possible only using RxJS operators
You can try something like this
sub
.asObservable()
.pipe(
concatMap(x =>
from(x).pipe(
filter(x => x.weight > MINWEIGHT),
toArray()
)
)
)
.subscribe(console.log);
The key idea is that you transform each array emitted by the source in a stream via the from operator and then, on this single stream related to a single array, you apply the rxjs filter and toArray logic.
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