Singleton Pattern - Design Patterns 

Thanks! I really appreciate it. I always put in extra time researching and working with any technology/topic before I record a video on it even if I already know it really well, since I want to make sure I understand all the intricate details so I know which parts are the important parts I need to explain in a way that makes sense.

@@WebDevSimplified And I really appreciate your efforts to bring us the best way to absorbe, sometimes, complex subjects and break them into tiny pieces easily to understand and digest.... hope to see much more great content from you =)

Thank you. My channel has already grown a lot the last few months. I can't imagine even more growth.

And now your words became real. Just last week 20 thousands people subscribe to this channel!

Agreed. And the export is the class itself, because whenever you run new FancyLogger(), you will get back the same FancyLogger instance. and that is handled inside the class constructor itself. If you export the logger instance created, as shown in the video, the constructor doesn't need to be changed this way

Better use typescript instead of js and make the constructor private

Same question!

If you work in a team, you want other people to use it correctly. Let's say it's the company directive to get the log count. If a person would by accident instantiate FancyLogger, they'd make a silent error. People will get the wrong log count and won't know that. If you make a class, you should make sure that others will use it correctly.

Yeah I also didn't get that, Kyle already solved it in the constructor, so why can't the other files just the keep using the instantiating with the class?

Don't Know about JS but as for Java a class cannot be static , only its members can be static. A static member can be access by all instances of that class.

Here is a sample code for Java Singleton Class , which may clear the difference between Singleton and Static Member

public class Singleton { private static Singleton instance; private int value; private Singleton(int value) { this.value = value; } public static Singleton getInstance(int value) { if (instance == null) { instance = new Singleton(value); } return instance; } public int getValue() { return value; } }

Yeah, that way you only have one connection and it's easier to manage

Depends on the use case / how often you make calls to your db. Look into database connection pooling

Thanks! Zeppelin is an incredible band and always enjoyable to listen to.

Nice. What makes it your favorite. For my the command pattern is one of my favorite.

@@WebDevSimplified is just that since i started coding with gwbasic back in the 90s there was no patterns like today and without any special reading when i was 10 and discovered i could share data info among different "screens" by using a common "module"(even in today's vb.net is still been used) that was so excited for me as a kid. so is my favorite just for nostalgia reasons 🤣🤣🤣

@@johnnyxp64 That makes a lot of sense. Nostalgia is pretty powerful. For me the command pattern just really opened up how powerful clean code and design patterns can be which was really exciting.

@@WebDevSimplified makes sense. is one of the pillars in OOP (command pattern) in my opinion and everything that uses encapsulation is helping the coder to focus on what matters and keeps indeed a clean and more readable code. 😎

1. It's mean that you set static property called 'instance' for your class X. 2. In the class like any other static fields. 3. Difference is that if you use this approach method you can't define an instance property without creating an instance of this class. class MyClass { constructor() { if (!MyClass.instance) { MyClass.instance = this; } return MyClass.instance; } field = 42; } console.log(MyClass.instance); //undefined const myClass = new MyClass(); console.log(MyClass.instance); //MyClass {field:42} (Or in your case 8) So all next instances will be known that you've already created some instance and instead of returning new X they will return that instance const newClass = new MyClass(); console.log(myClass === newClass); //true

Thanks!

You are completely right. I generally avoid this pattern, but there are cases where it can be useful.

Thanks!

Thanks!

1). npm init (under folder singleton) 2). Add .js (import logger from './FancyLogger.js')

The singleton design pattern and databases are two completely different things. A database is a place to store information in an efficient long term place while the singleton design pattern is just a way to structure code so that you only ever have one global version of an object.

​@@WebDevSimplified Then using a database to store an objects is waste and misused? I'm having a plan to create a small database for re-merging every properties on the same column and sending them back to the each instances just like how singleton does.

@@juanyang838 I am not sure what you mean. A database is for permanent storage of things you need to access later. I do not really know what you are trying to do.

Thanks! Led Zepplin is such a great band.

Hi dude im also Akhil M

Have a great day!