Observer (TypeScript Design Patterns)

[@supermetan3571]

hands down, best tutorials on youtube, keep it up. You are an impressive teacher, very easy to follow

[@simplyexplained]

Thanks a lot!

[@mohammadmohabsarhan3961]

I must say, whoever invented this is just a genius, Thanks for the tutorial.

[@chikamichi]

Beware, in this video Xavier calls what's observed, a Subject. Yet the proper naming is "Observable". A Subject is an entity that may act as *both* an Observable and an Observer. It's the building block used in implementing Pub/Sub systems (think chat app, typically).

[@ojuliomiguel]

Good!

[@jananpatel9030]

7:47 why are we saying weatherStation.registerAObserver(this). Why aren't we using this.subject? This is the only part that confused me

[@iqbalibrahim4713]

Thank you for the video, before this I saw a video about observer pattern elsewhere but was not able to understand when needed more than one observer, your video explains really well and with good examples, deserve a like and subscribe

[@elijah6283]

Thank you, this is one of the best explanations of the observer design pattern implemented with TypeScript.

[@raj.blazers]

Tutorials are damn good. Please post more design patterns.

[@muliaarifandynasution525]

Awesome! I hope there are more videos about design patterns like this.

[@hakart411]

thanks for your great tutorials there is one tiny problem in 'removeObserver' method . actually the problem is for 'splice' method and this is it : if passed observer to removeObserver method does not exist in the observers array the index become -1. then the splice remove last item from the observers array

[@muhammadramzanali584]

Simply Explained! Great work!

[@abdulkadirguven1173]

Simple and clean explanation.Thank you ;)

[@figidon-software]

If you are building a web-project you can also implement the observer pattern with events. Assuming you use jquery, it's as simple as: 1. Trigger the event with *$('body').trigger('weatherStation:tempChange', newTemp)* 2. Listen to event triggers with *$('body').on('weatherStation:tempChange', (e, newTemp) => { // logic to handle newTemp})* If you goto the Dev Tools you can see that youtube makes heavy use of custom events. In the Elements tab you can select an element, then see all the Event Listeners attached to it.

[@Videosuser]

You are an impressive teacher,

[@Antonym1978]

Thanks for a clear explanation!

[@lautaroleonhardt2600]

Need more videos like this!

[@IslamGadzhiev]

Why mixing the responsibilities and logic of observability between display classes and the weather station ? That is - in the constructor in Fan and TempretureDisplay classes you do: `weatherStation.registerObserver(this);`, which means that the Observer instance inside make the Subject register it. It's wrong, i think, instead the cleaner approach would be to make the Subject register the Observer separately from the Observer being able to update based on the Subject notifications.

[@ManontheBroadcast]

Crystal clear explanation .. even i am not familiar with the TypeScript syntax but just plain JS , for once i think i managed to grasp this concept ...Thanks for sharing your knowledge ...

[@simplyexplained]

+Man-on-the-Run Thanks man! I'm really trying to do my best with the videos.

[@lukezzz420]

Hi, great tutorial! One question, shouldn't you set the return value of the functions in the interfaces to void if they return nothing? Else it will have the return type any...

[@webmaker6576]

Really Deserve appreciation

[@Eriksonmagno]

Awesome tutorial

[@H3000-v7i]

Why would you add a reference to the subject, in the observer?? If you the remove a observers, they will still carry unused reference. Seems like bad code to me? please correct me if im wrong.

[@NagatoKamiPain]

can you make this video with function as well?

[@a.durgadevi8052]

best tutorial . Thank you

[@bhanuprathap3170]

Great tutorial

[@creative-commons-videos]

Can you please make a Playlist on building ORM in typescript using Object Oriented Programming, Just like Laravel Eloquent ?

[@andredejager3637]

Awesome, thank you

[@hemanth6951]

In Android also we are doing using same design pattern for callback methods

[@coplain]

Savjee .. Thanks for the tutorial . One question though .. Imagine I have say I have large # of observers (say a billion) . Since we are using foreach loop to notify and its a O(n) operation ..by the time it reaches last observer another event happens the notify loop starts all over again.. how would we handle this scenario ? Let us say in environment like high frequency trading where trading happens in nanosecond time frames.. how can we handle this issue .. Thanks

[@simplyexplained]

Hmmm you will always have O(n) is this system. Nothing you can do about that. However you could make your observers asynchronous and distributed. Being async will allow you to quickly go through the foreach loop (since you don't have to wait for the return values). After that you spread the load among a number of computers who all work on handling a part of the observers.

[@coplain]

Thanks

[@ys1197]

5:40 thank u :3

[@melitt6813]

good job! thanks!

[@vladimirrabtsun]

Wow! Cool!

[@aleksd286]

Thanks man

[@hazartilirot1014]

The examples are stolen from Head First Design Patters. :D

[@lagiator]

helpful, thanks!