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RxJs switchMap vs mergeMap - Intro to Flattening Operators (2021)

In this video, we are going to start learning of flattening operators in #rxjs, namely MergeMap (former FlatMap) and SwitchMap. We will see how data flows in flattening operators and we will visualize it using mental models from real life.
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🕒 Time Codes:
00:00:00 - Intro;
00:00:52 - Mental model for mergeMap & switchMap;
00:06:11 - Let's code it!;
00:24:47 - Outro;
#rxjs #angular #webdevelopment

Пікірлер: 76

  • @stepandemchenko9870
    @stepandemchenko98702 жыл бұрын

    Finally I understood difference between switchMap and mergeMap. Thanks!

  • @THEWilliamchik
    @THEWilliamchik Жыл бұрын

    Wouldn't be a lie if I say this is the best explanation I've seen. Very helpful, thanks!

  • @aleksandrm3466
    @aleksandrm34662 жыл бұрын

    I want to receive notifications about such videos every day. Thanks alot, perfect job :)!

  • @abhiramm4941
    @abhiramm4941 Жыл бұрын

    Bruh. You are a life saver. I have read 100 articles and seen tonns of videos for understanding the difference between switchMap() and mergeMap(), but none of them explained it butter clear as you😍😍. Especially the real life example of order and chef. That was spot on🤩

  • @antondoit
    @antondoit8 ай бұрын

    Fantastic description. I am so happy that i found you on youtube 🙂

  • @usmanmuhammad157
    @usmanmuhammad1572 жыл бұрын

    This is was he best possible way to teach these operators. Thank you.

  • @romanlesko6420
    @romanlesko64202 жыл бұрын

    Дуже круте пояснення. Дякую!

  • @ichr
    @ichr2 жыл бұрын

    Another great video! I love this interactive example! Thank you so much! The only problem I have is that I become hungry from minute zero :D

  • @balaeinstein8710
    @balaeinstein87102 жыл бұрын

    this is awesome . Thanks a lot . please continue this series . we want to learn RxJs this way

  • @rakeshbaswaraju5324
    @rakeshbaswaraju532410 ай бұрын

    The truth is, this is the best explanation I have ever seen...Thank you

  • @fito443434
    @fito4434342 жыл бұрын

    I love angular, and I really love this channel .. great stuff!

  • @DecodedFrontend

    @DecodedFrontend

    2 жыл бұрын

    Thank you! :)

  • @hubert.t4243
    @hubert.t42432 жыл бұрын

    I love that you are using the Dürum analogy, it is so much fun to watch. I didn't realised until now that you are actually living in Vienna. Servus :)

  • @nirmalkumar7941
    @nirmalkumar7941 Жыл бұрын

    The best video for these topics

  • @pawekoaczynski4505
    @pawekoaczynski4505 Жыл бұрын

    This is the video that finally made it click for me. Thanks c:

  • @LidiyaChernomorova
    @LidiyaChernomorova2 жыл бұрын

    Really cool explanation with orders, THX!

  • @abhishekrathod982
    @abhishekrathod9822 ай бұрын

    Amazing explanation!!

  • @balajeebala7810
    @balajeebala78102 жыл бұрын

    Awesome as always ❤️

  • @DecodedFrontend

    @DecodedFrontend

    2 жыл бұрын

    Thanks a lot!

  • @facuabdo
    @facuabdo Жыл бұрын

    Such an awesome explanation. Thanks a lot for this!

  • @DecodedFrontend

    @DecodedFrontend

    Жыл бұрын

    Glad you enjoyed it!

  • @kirilldegtyarev5668
    @kirilldegtyarev5668 Жыл бұрын

    Дмитро, спасибо за ролики очень всё понятно, наконец-то разобрался что есть что) Пока что новичёк в RxJS.

  • @Doktornikita
    @Doktornikita2 жыл бұрын

    Thank you very much! You make great content! 👍🔥🔥🔥

  • @HagbardCelineOnRust
    @HagbardCelineOnRust2 жыл бұрын

    ty for the upload. I constantly fail on rxjs since iam from promiseland. combining streams, taking value from one and put into another and then even determine another return type/interface, really high learning curve

  • @DecodedFrontend

    @DecodedFrontend

    2 жыл бұрын

    I completely understand you :) I have been in the same boat few a few years ago and for me, it was a very tough time. But I can say for sure that once you get Observables you will be asking yourself "How did I live without Observables before" ;)

  • @dariooliveira5004
    @dariooliveira50042 жыл бұрын

    Perfect explanation, thanks!!!

  • @Rob34570
    @Rob345702 жыл бұрын

    Took me a while to work out that the Durum chef was making Kebabs (as we down under know them). Greetings from Australia 🙋‍♂️ Your channel is awesome!

  • @ariMuayad
    @ariMuayad2 жыл бұрын

    So helpful and such an amazing way of explaining.

  • @DecodedFrontend

    @DecodedFrontend

    2 жыл бұрын

    Glad it was helpful!

  • @tarasshevchuk8477
    @tarasshevchuk8477 Жыл бұрын

    Дякую за корисну інформацію !

  • @mykolastrashok9986
    @mykolastrashok99862 жыл бұрын

    It's awesome video!!! Thanks you for that!

  • @praktycznewskazowki6733
    @praktycznewskazowki67332 жыл бұрын

    its so good practical example! :)

  • @jamesquinlan2638
    @jamesquinlan26384 ай бұрын

    switchMap works when the second order is from the same customer (who has decided to change his order). The second order requires a very different preparation (with different utensils) and so a second chef is told to prepare it whilst the first chef tidies up his work space.

  • @alextiger548
    @alextiger548 Жыл бұрын

    Nice man!

  • @markusingvarsson2146
    @markusingvarsson21462 жыл бұрын

    Awesome video!

  • @praecantat1o
    @praecantat1o2 жыл бұрын

    I'm really surprised that angular and rxjs can do such unbelievable things. It's kinda magic!

  • @RamKumar-es3mp
    @RamKumar-es3mp Жыл бұрын

    Thankyou. Great content

  • @metorado
    @metorado Жыл бұрын

    You are the best❤

  • @radvilardian740
    @radvilardian7402 жыл бұрын

    I was looking for my issue aboit this couple minutes ago, this notification pops up

  • @cangua4462
    @cangua4462 Жыл бұрын

    thanks sir , it helps me so much

  • @leonbenjamin7891
    @leonbenjamin78912 жыл бұрын

    Excellent video. thanks!

  • @DecodedFrontend

    @DecodedFrontend

    2 жыл бұрын

    You are welcome 🤗

  • @beeTechSE
    @beeTechSE2 жыл бұрын

    It's awesome video!!! Thanks, if possible, make a video about Angular change detection

  • @mustafasange
    @mustafasange2 жыл бұрын

    Great! 👍

  • @AmarSingh-uw1db
    @AmarSingh-uw1db10 ай бұрын

    Gratitude Sir ❤❤❤

  • @issam9077
    @issam90772 жыл бұрын

    thank you

  • @ankitachoudhary716
    @ankitachoudhary7162 жыл бұрын

    You're awesome

  • @RAJU9622
    @RAJU96222 жыл бұрын

    Awesome video

  • @DecodedFrontend

    @DecodedFrontend

    2 жыл бұрын

    Thanks 😊

  • @Isa-oo8mz
    @Isa-oo8mz2 жыл бұрын

    Great video! Could you create video about zone in Angular?

  • @frontend3409
    @frontend34092 жыл бұрын

    I came here to make myself ensure about those. I think @ 4:35 you could put two money icons inside mergeMap functions to picture this better. At switchMap example 5:36 i would say that there is only one chef in the kiosk and (because i felt sorry for him, that he got fired xd) he can't do two dishes at once and he throws away the first one in the recycle bin and started to making the dürüm for the guy in the glasses xd TBH, I think if i didn't learn earlier about those types of maps i would get that video, because of complexity of the objects. I would change the order of the names of keys in objects, like { customerId: 1, amount: 2}. Maybe i would do few buttons (one for adding 1 amount of dish, second for making 2 and third for making 3 dürüms). Besides all those things it is a very nice video!

  • @alexanderbell7736
    @alexanderbell77362 жыл бұрын

    Thanks!

  • @DecodedFrontend

    @DecodedFrontend

    Жыл бұрын

    Just noticed your super thanks. Thank you so much for your support! :)

  • @AbdullahAMalik07
    @AbdullahAMalik072 жыл бұрын

    finally the mystery solved between mergeMap and switchMap ^_^

  • @Afdac247
    @Afdac2472 жыл бұрын

    You come make a wealth of KZread videos based on the rxjs operators before you know it you're going to be head of angular project. Also concatMap and exhaustMap are related to these operators as wel

  • @oren-karaso
    @oren-karaso2 ай бұрын

    Great comprehensive stuff as always, tnx! A little question though: at 21:30, according to the example, when you clicked for a new order (2nd customer), and then clicked once on every product, durum was prepared for both customer 1 and 2, even though you only clicked each product once. Is that intentional? Or should we try to modify our logic so one click on every product in this scenario would only advance the product by 1 instead of by 2?

  • @moonstone234
    @moonstone2342 жыл бұрын

    I cannot find anywhere how does switchMap internally work. Does it unsubscribe inner observable? If so, the word "unsubscribe" should be used to describe its behaviour rather than "completes" because you cannot complete observable, am i right? In that case saying switch map completes inner observable doesn't make sense to me.

  • @DecodedFrontend

    @DecodedFrontend

    2 жыл бұрын

    Hi Moon, thanks for your feedback! From what I see in the switchMap's source code, it unsubscribes from active inner observable before scheduling the new one. Yes, you are right, probably I misspell it and said "completes" meaning unsubscribing. My mistake, sorry.

  • @kamalmohansinghrana1381
    @kamalmohansinghrana13812 жыл бұрын

    How can we prevent API being involked multiple times without using ngrx actions exhaustMap(). Because user press button multiple times often.

  • @DecodedFrontend

    @DecodedFrontend

    2 жыл бұрын

    Why don't you want to use exhaustMap()? It can be a good choice to prevent unnecessary http calls until the active http call completes. Also you can use switchMap if you want to cancel already active API call and fire the new one.. You can also try to use distinctUntilChanged, in some cases it can help to prevent calls if http call params (e.g entity id) has not been changed since previous time. Well, it is hard to say which solution is the best in your case, it very depends on a stream, params, etc.

  • @codeSurvivor
    @codeSurvivor2 ай бұрын

    getting hungry 😉

  • @DecodedFrontend

    @DecodedFrontend

    2 ай бұрын

    😁

  • @TymurDaudov_aka_tymfear
    @TymurDaudov_aka_tymfear Жыл бұрын

    Давай exhaustMap - менеджер берет деньги со всех , а получает только первый 😂😂

  • @rnd_equilibrium
    @rnd_equilibrium2 жыл бұрын

    Hay Dmytro! As always great video! But I have some questions. At 16:40 u clicked the buttons, shouldn't there be a value in the corresponding subjects, so if u press the order button shouldn't you get an immediate value out of the delivery stream? 🤔 And also at 23:21 u can see in the array of ingredients that the cabbage1 is left from the previous stream. Isn't that a problem when u zip streams and one of the streams get behind, cause i could imagine if someone uses the zip operator to kinda get streams in sync, u know? I don't know if these questions even makes sense, but they came to my mind. ^^" Oh and also first

  • @DecodedFrontend

    @DecodedFrontend

    2 жыл бұрын

    HI! Thanks for the feedback :) Regarding you first question: No, we should not get immediately value. It is because streams are lazy and they take values only when you call subscribe method.. before I click "order" mergeMap isn't subscribed to durum$ stream, so all events in this stream are kind of ignored and only when I click "order" button mergeMap subscribes to durum$ stream and starts to receive values from it but only values which are coming after the activation. The second question: It looks like the problem because of global counter... In fact that cabage1 belongs to the second stream (so technically you can treat it as a cabbage 2).. I probably had to reset counters every time the stream completes to avoid miscounting.. Sorry for the inconvenience, my bad :(

  • @rnd_equilibrium

    @rnd_equilibrium

    2 жыл бұрын

    @@DecodedFrontend Ah ye you'r right, because it isn't a BehaviorSubject, so it doesn't get the latest value. My mistake. :D So to clear it for me, the zip operator always keeps the streams 'in sync' or could't it be, that one of the zipped streams gets ahead/behind on a emitted value. I know this is more a question for the other video, but ye, it just thought about it. ^^"

  • @DecodedFrontend

    @DecodedFrontend

    2 жыл бұрын

    Exactly, it is not a neither BehaviorSubject nor ReplaySubject. And yes, zip operator keeps value emissions kind of in sync. So if you have 3 streams which are counters, with different time interval and which over some time emit values like 0..1...2..3..4... then the output of zip operator will be always like: [0,0,0]... [1,1,1]... [2,2,2]... [3,3,3] ... and so on.

  • @rnd_equilibrium

    @rnd_equilibrium

    2 жыл бұрын

    ​@@DecodedFrontend Ah great, thanks for clarification! :) Again great videos, definitely keep it up! 😊

  • @DecodedFrontend

    @DecodedFrontend

    2 жыл бұрын

    @@rnd_equilibrium Thank you! Glad you liked it ;)

  • @akshayporwal8802
    @akshayporwal8802 Жыл бұрын

    cann you pls share source code!

  • @haroldpepete
    @haroldpepete2 жыл бұрын

    Bien pollo crudo

  • @valikonen
    @valikonen2 жыл бұрын

    You make a big mistake letting zip from previous video, it is much harder to see all code....

  • @VolRecon
    @VolRecon2 жыл бұрын

    Dmytro.. from Poland? 😏😏

  • @DecodedFrontend

    @DecodedFrontend

    2 жыл бұрын

    Almost! From Ukraine :)

  • @magneticartist
    @magneticartist2 жыл бұрын

    Creating too many subjects takes up a lot of memory, just create one as observable: anything = Subject() anything$ = anything.asObservable() and pass an object with the specified type and value {type:"",value:""} anything.next({type:"food", value="bread"}) subscription = anything$.subscribe( object => if( object.type == "bread") do etc... with object.value )

  • @Nine_Tails
    @Nine_Tails Жыл бұрын

    я канешна все понимаю, но хотя бы субтитры на русском запилили(((