Real-life: expand() cursor pagination

With expand, load pages 1 -> 2 and flatten the items into a stream.

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const { of, EMPTY, from, expand, mergeMap, map } = Rx;

const pages = {
  1: { items: ['a'], next: 2 },
  2: { items: ['b'], next: null },
};

const result$ = of(1).pipe(
  expand(page => pages[page].next ? of(pages[page].next) : EMPTY),
  mergeMap(page => from(pages[page].items))
);

result$.subscribe(value => console.log(value));

script.ts // TypeScript

CONSOLE · Console output

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