Javascript Design Patterns #5 - Observer Pattern

What is the Observer design pattern?
The Observer pattern is a design pattern that offers a subscription model in which objects (known as 'observers') can subscribe to an event (known as a 'subject') and get notified when the event occurs (or when the subject sends a signal). This pattern is the cornerstone of event driven programming.

📚Materials/References:

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[tahasaleh]

Are you a subject? because as an observer, I just subscribed!

[js_programmer]

im not gonna lie..you are the best teacher I've ever had, you literally talk to me like i'm 5 years old. thank you.

[DevSage]

Note: Instead of using fn.call(), you could also just use fn(). They are the same!

[CarlitoProductions]

This is by far the best explanation I could find on the subject. Great job with this video

[HologramJay]

You're a talented teacher, DevSage. Thanks.

[Strasbourgeois]

What was demonstrated so nicely in this video is the pubsub pattern. It resembles a lot to the observer pattern and these two are used interchangeably most of the time. There is a subtle difference between them though: pubsub subscribers are not aware of the subject whereas observer subscribers have a reference to the subject

[stud_-ylbu]

I finally understood what is going on goooing man.

[peristiloperis]

You've just got a new subscriber. Great lesson. Keep the good job!

[MegaVladikslavman]

The best explanation I seen on YouTube. Thanks a lot!

[KnownTechnical]

You are the only one who has nicely explain these patterns. Good Work!

[juraev]

Clear explanation with simple examples. Thank you!

[yamogebrewold]

This was a great explanation of how an event listening system would work in its essence.

I'm not sure if it's a good practice to override the prototype object like you did, but rather extend it.

[onlyme]

like how you keep it concise and simple ty

[RyanFromUltrasound]

Curly braces on new lines. Prototypal over Pseudoclassical. Based.

[neuodev]

Thanks for you "Observations"!

[MrTomro]

subbed, i already love this channel and ive only seen 3 vids

[quarantinemade]

Thanks for such a simple and amazing explanation👍

[Videosuser]

One of the best explanations! Thank you.

[evgenylevchenya]

One little thing: your code allows you to push the same observer multiple times and it will fire it up multiple times.
It should have check for having observer in array before push

[SiegfriedxD]

Finally understood this pattern. Thank you very much!