map vs switchMap in RxJS

Question

I read the documentation of switchMap and map, but I still don\'t completely understand the difference. Are there some cases where it does not make a difference at all?

Answer 1

Are there some cases where it does not make a difference at all?

No. They are two totally different beasts. switchMap is expected to return an observable, map can return anything. Their application is different. It would typically go like this:

someStream$.pipe(
    switchMap(args => makeApiCall(args)), // must return a stream
    map(response => process(response)) // returns a value of any shape, usually an object or a primitive
).subscribe(doSomethingWithResults);

There are other operators similar in nature to switchMap: mergeMap (AKA flatMap), exhaustMap, concatMap (and there are cases when all those amount to more or less the same thing), but not map.