Javascript Design Patterns #1 - Factory Pattern 

Great video. Your channel is superb. Just one request, please make the code legible for mobile screens. I usually watch these kind of videos on mobile when I am taking a break or something. I am sure there are others who prefer mobile as well.

I'm glad it helped you!

Appreciate you

@@DevSage Why aren't you passing it in as a param? I feel like that gives you more of an overview of what the function does. Well.. maybe not in this example but I think you get what I mean right

@@onlyme0349 I suppose either way could work

💪🏾💪🏾💪🏾

It's probably because of his Java background (or C, or C++).

Taht's how its done in C#, I find it very elegant and its easier to read

I came to the comment section to find this comment xD

I think I used to see or do this when I was working with java/c#. And probably the ides would format it that way

A long time ago back in school there was actually 2 competing sides and this was 1 of them, but I think eventually no one does it anymore. I dont know anyone who does this now lol

Glad I could help! 😁

You're welcome!

Appreciate it. Nice to meet you 😁

I appreciate you

Thanks!

You're right. Never noticed that until now haha. Thanks for the sub

Thanks 👍🏽

Glad I could help

Glad it was helpful!

Also, every time when you are reading the code, you probably don't know what that numbers is

I appreciate it

Didn't feel like it

You're welcome!

You're welcome

Yes, using numbers would get a little confusing. This pattern is more useful when you're using a strongly typed language like TypeScript where you could make use of enums instead of raw numbers.

You are correct

Glad you enjoyed it!

I don't think he realised he had to answer this question! Lol.

@@rutwickgangurde3247 yeah, it's not a rhetorical question, haha

I really hope this gets answered as I'm wondering why he doesn't create classes for the developers and testers instead of functions

Thanks for watching!

Glad you liked it!

Maybe it's just good to practice structured code?

Hmn i don't like over complicating for the sake of it, it would be nice to see some situations where the benefits of this structure can be seen

@@omirrrr True, tbh I'm just starting into design patterns because I just had a job interview where they asked me about them, so I'm not sure either.

Because you have a centralized factory for a type of objects. If you for instance get a json with multiple employees you can then just call employeeFactory.create(name, type) instead of implementing the switch for everytime you import data. And if you change Developer to take (name, salary) you just have to change it in one place. As soon as multiple devs work on it, its easier to have one reference then to dig trough everyones code if they called new Developer(n), as an example.

@@benjaminbaer5485 honestly your examples made the penny drop for me. i feel a lot of design pattern explanations (or maybe even tech explanations in general) focus only on how to do the thing but not what the benefits are when compared to other solutions.

Correct! And thank you!

I guess you don't actually need the factory function. Yeah you could return employees from the factory itself

@@DevSage ok. What's the benefit of the instance of the factory function then? Just curious as I'm a beginner with JS 😛

This does not scale. For instance, if more unique properties are added to either employee type, they would need to be passed into the factory, which is just too much redundant code. Much better to have an object for each employee type that can be expanded upon.

Also your switch does literally nothing lol. Hopefully after 2 years you figured this all out on your own though.

You are right.

“This” inside say would refer to the window object. Using call or apply would pass in what “this” you are implying

Thanks!!

Glad you like it

You could certainly do that, yes. That might actually be an easier way to do it. I just wanted to make sure the general idea of the pattern is understood

Yes, this is not clean factory pattern. In this example factory has dependency on Developer and Tester. Actually EmployeeFactory have to be abstract class and we need two subclass like DeveloperFactory and TesterFactory. So abstract factory class not depends on concrete Developer or Tester implementation. And we can easy add another class like Designer, and create DesignerFactory implementation of abstract factory class. So our code is open to extension and close to modification. In the video example factory is not close to modification and open for extension. And also Factory need some additional logic(interface) inside factory itself. Otherwise it useless.We can add some methods to Factory like, work() and each class Designer Developer and Tester will works, but in they way.

You're welcome!

Explain it to me

Yes. The functions used here are Constructor Functions. In JavaScript Factory Functions are regular functions. JavaScript is not an Object Oriented Programming language like Java but it supports OOP. Some programmers do not like using Constructor Functions in JavaScript because of how the 'this' keyword works and how it's reference changes depending on the program. Below is an example of how we could rewrite the code using Factory Functions : function developer(name) { let newDev = { } newDev.name = name; newDev.type = "Developer"; return newDev; } function tester(name) { let newTester = { } newTester.name = name; newTester.type = "Tester"; return newTester; } function employee( ) { const create = (name, type) => { switch(type) { case 1: return developer(name); case 2: return tester(name); } } const say = ( obj ) => { console.log(" Hi I am " +obj.name+ "and I am " +obj.type); } return { create, say }; } const emp = employee( ); const employees = [ ]; employees.push( emp.create("Patrick", 1) ); employees.push( emp.create("John", 2) ); employees.forEach( ( obj ) => { emp.say(obj) }); Apart from this, I think the explanation in the video is pretty good!

www.dofactory.com/javascript/design-patterns addyosmani.com/resources/essentialjsdesignpatterns/book/

DevSage thanks, great playlist.

Yes!

You're right!

Thanks!

Thank you 😊

You're welcome!

No the strategy pattern is this -> ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-SicL4fYCz8w.html

It's a creational pattern

Haha well no that's not my channel. But after going to that channel and listening for myself I can see/hear EXACTLY what you mean lol

I'm doing good man. How about you?