Map, switchMap, mergeMap, flatMap, concatMap, exhaustMap in RxJS - what is the difference?

Learn what is the difference between map, switchMap, mergeMap, flatMap, concatMap, exhaustMap in RxJS and what method you should use in what case. Sometimes you see the different methods used for the same case and it is even more confusing.

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TIMESTAMPS
0:00 Introduction
0:51 Map RxJS
3:06 MergeMap and FlatMap RxJS
4:55 ConcatMap RxJS
5:55 SwitchMap RxJS
6:37 ExhaustMap RxJS
7:18 Real example

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[SilvanAngele]

love his tutorials, very good explained always.

[ghkpr]

lol, yesterday night I searched for monsterlessons academy mergemap flatmap switchmap, and here it is, thanks :D

[collectingretrotech]

excellent explanation and example, I don't think anyone could have explained this subject better than what you just did : ) THANK YOU

[gabriellavoro]

You put out very good content, I've been enjoying your videos.

[kiwi]

this channel is gem. you deserve more subs.

[pauldudley]

wooow, I've been struggling with this for a long time trying to find an explination I understand and you broke it down so will wih the delay added in to slow down the function.
Fantastic content

[MM-tsjy]

"You will learn once and forever..."
I'm now ashamed to admit this is the second time I check this video this week 🤣

[programmingpurpose]

Love your videos mate. You are best in angular ❤

[ekchills]

love this so much exactly what I needed

[atmospheric_b]

thank you very much! That`s an ideal tutorial!

[raghavendrajyante]

Great video..Thank you..
I have a small question.

exhaustMap emits the first observable and ignores all subsequent observables until the first one is complete.
The question is, What happens once the first observable is completes??
will it ignores the rest of the observables?? or
will it emit the next observable after completing the first?

[brenooandraderox]

That's awesome, thank you for sharing this useful content!

[swapnith]

I understood all this concepts of rxjs, so i am preparing for interviews so this will help me a lot tnx but small confusion still not understood what is diff of mergemap and flatmap, anyhow great job man

[KostasOreopoulos]

A nice example to remember is the following:.
Imagine that you have a chair to read the "data" of the observable. In switchMap and exchaustMap we have just one chair for the observables to sit as the pass in front of the chair.
In switchMap. When an observable passes in front of the chair, the observable sitting on the chair should get up and leave and the new will sit. In the exhaustMap case, if the sit is taken, the observable passing by should leave and all its data are lost.

Now concatMap has still one chair reader but has a big hall and keeps observables in the waiting room. in a queue. When an observable completes, the next one takes its place at the chair.
MergeMap has many chairs. As the observables arrives at the center, it takes a seat, and we read its data. When it completes, it gets up and leaves, and we publish its data. Not in the order it came.

I guess the limits in the number of MergeMap chairs is the same as in PromiseAll.

[MukeshSharma-xddn]

Fantastic video.... Many thanks.. Learnt a lot!!!

[waleedsharif]

What do you think of styling, which one of these should we use in react: mui 5, bootstrap, react styling component, css, tailwind?

[CodingAbroad]

It sounds like in most cases you probably wouldn’t see a difference between switchMap, mergeMap and concatMap unless your ui had a element such as a select dropdown to quickly change the results and the api being a bit slow

[rhnkashyap]

So, concatMap and switchMap resolves race condition if we are triggering a single API a lot of times and wants the last request's response as final output. RIght?

[Georgii]

Great tutorial, thanks. In your code, if we write : from([0, 1, 2, 3, 4])
.pipe(operator((x: any) => from(x).pipe(delay(500))))
.subscribe(...) so we suppose we use 'from' operator inside another 'from' operator (instead of "of" as you did). And there is nothing in the console. So why it does not work if we call 'from' inside 'from' ?

[arielhillel]

In which courses do you talk extensively about these topics?