1. When do you use switchMap, mergeMap, concatMap, and exhaustMap?
Difficulty: MediumType: SubjectiveTopic: Core RxJS Operators
switchMap cancels previous inner requests (great for typeahead). mergeMap runs all inner requests in parallel (best throughput). concatMap queues inner requests one-by-one (order guaranteed). exhaustMap ignores new triggers while one inner request is running (good for login/submit buttons to avoid double submit).
Example code
fromEvent(input, 'input').pipe( map((e:any) => e.target.value), debounceTime(300), distinctUntilChanged(), switchMap(term => this.api.search(term)) ).subscribe(results => this.results = results);