JavaScript Classes vs Prototypes

[@judaspriest33715]

I can probably count on one hand how many truly clear and straight forward youtube coding tutorials I've watched, this is one of em, hitting subscribe!

[@DRocksRecords]

Yeah each time I stumble on a video he made I feel like someone with confident knowledge is showing something useful. I subscribed too

[@machineshouldbe]

My head is still spinning, but this breakdown helped me understand how to use classes more. Thank you so much.

[@IONYVDFC]

Great video! Being an old-school C++ developer, I personally never understood why JavaScript ever needed to borrow the class syntax. One cannot really deny anymore that classes exists in JavaScript, they surely didn't. I prefer the syntax 'prototype' above 'class'. Many early C++ book editors around 1990 had a hard time explaining what a class is all about, almost apologetic for the confusing word choice. A prototype really says what it does, as it shapes how the instantiated object will look like, while a class has nothing to do with classification.

[@rotrose7531]

I never dreamed I can understand these class things, but after this tutorial, those abstract things go straight into my head without any resistance. legend teacher, as always thank you.

[@wick12298]

Its actually Prototype, classes don’t exist in JS. Also, this is “this”. And its also an Object

[@igoroliveira9146]

Steve, you are the ONLY ONE I found online, that explained well enough so I could understand, I always tried to find a relationship (a kind of "translation") between functions and classes and you simply explained it. Perfect video. Thank you very much.

[@LR-bc8js]

Same thing here bro :)

[@NourHomsi]

I've been a Javascript programmer for more than 10 years, but suddenly, you opened my mind to a whole new sight to OOP in Javascript !!

[@Snoo29293]

At 11:13, if you set the prototype of EmployeeP to PersonP.prototype, the EmployeeP.__proto__ becomes the PersonP.prototype, and the EmployeeP.prototype stays the same it was, that's what happens for me at least. Because of that the methods inside PersonP.prototype cannot be called through the objects created by EmployeeP. I don't know if I did something wrong, but to fix that I simply wrote Object.setPrototypeOf(EmployeeP.prototype, PersonP.prototype), so now the prototype object of EmployeeP function is a child of the prototype object of PersonP function, I think that's how the prototype chain for classes is too.

[@josiahtobas9172]

Yooooo...been searching for a clear instructional video on this topic, finally found it. Thanks a lot.

[@arinamartens6858]

you are the best! you have nice voice and speech and so good at explaining, thank you

[@bulldawg4498]

As an advanced novice JS coder, I always found 'prototypes' confusing ... Your video makes the case for the class paradigm vice prototype model in my view ... Coming from the Java and Python world, classes and subclasses are the way to go and are more OOP than 'prototypes' ...

[@SteveGriffith-Prof3ssorSt3v3]

They both do the same thing internally. Both syntaxes are working with prototypes. The Class syntax was partly added to make the transition easier for people coming from languages like Java. Partly it was yet another attempt at trying to simplify something that has been a confusing mess for 20 years.

[@LR-bc8js]

I think in 11:16, the line should be Object.setPrototypeOf(EmployeeP.prototype, PersonP.prototype) instead. Great video! I love it!

[@SteveGriffith-Prof3ssorSt3v3]

Yes that line was changed in the description and in the code gist.

[@gayathrisathyan3892]

@steve griffith : Hello Steve. This is really Awesome. By far the best Explanation ever. All your Videos are Awesome. Keep Rocking. A Small Clarification, I feel it has to be Object.setPrototypeOf(EmployeeP.prototype, PersonP.prototype). [ You have written EmployeeP. This causes an error and I'm not able to call getDetails Function from the Base Class. ] Please do correct me if I'm wrong. Thanks

[@SteveGriffith-Prof3ssorSt3v3]

Yeah. I fixed that in my code sample afterwards. I also have a new video that I did to visually explain prototypes - kzbin.info/www/bejne/ZmLNh5p5gJJ7jpY

[@gayathrisathyan3892]

Steve Griffith Awesome Man. Thanks

[@JT-mr3db]

A lot of libraries use the manual prototype method and there are some neat tricks you can do with it. I first saw this when analysing mongoose code. There are some challenges if you want to represent this with types in a typescript project, I found using class syntax to be less pain in that regard.

[@SteveGriffith-Prof3ssorSt3v3]

I definitely have things that I do with prototype and then there are some cases - Web Components, extending Events, extending Errors where I will use the class syntax.

[@kumargaurav4492]

Thank you! Steve, It's a great tutorial, and your explanation is really great. :-)

[@aaaaaab631]

Thank you so much. I am not good at english but your explanation is amazing. I can understand whole things. Thank you.

[@jholtkort]

Thank you for creating this. Very good!

[@jcoopsdrums8941]

Thank you so much, you have helped me sort out the details that were getting mixed up in my head.

[@Pareshbpatel]

JavaScript Classes and Protototypes beautifully explained. Thanks, Steve {2023-08-18}

[@michael.knight]

Excellent tutorial, thank you.

[@Maru-ge6jn]

No bs, straight to the point, clear explanations with clear examples. So underrated!

[@Claudia-hz4ly]

Omg! I finally understood prototypes - I have watched three different tutorials and I still did not get that...until I came across this video! Thank you so much!

[@barungh]

"It is important to understand that the class syntax is being interpreted as using the prototype syntax and that CLASSES do NOT exist in JavaScript." Great 👍

[@sahasrabhujaneuron5975]

This is exacly what I'm looking for! Now it makes more sense why the syntax in class is constructed in a bit of a weird way. Many thanks!

[@thippanayugesh8414]

this channel is pure gold.

[@ManjunathManja1227]

And so underrated.

[@ahmedelgaidi]

thank you it' s a really good one

[@westonpetersring]

You are a true engineer, thanks man

[@manjoujanzen9375]

great way to explain, clear and in a not too fast speed, so the brain can follow. thank you for the great tutorial.

[@federicoprat9093]

my god finally i understand the difference, Thank you man you saved me.

[@cuberos7430]

wuauu !!! You made it very easy . A lot of thanks, Blessings

[@FozIrenics]

How many times have I watched this video over the last few months? Lost count...

[@manishmate9991]

The beeeeeeeeeeest explanation ever. Thank you so much mate.

[@rongliao9255]

Great tutorial with super clear explanations! Thanks a lot!!

[@raymondji1006]

Hey Steve, thanks for making this video, very helpful! I think there might be a small error at the end, should it be Object.setPrototypeOf(EmployeeP.prototype, PersonP.prototype) instead? See: jsfiddle.net/xnu19ec3/4/ Also may be useful to touch on the difference between __proto__ and Prototype, I found that confusing to understand.

[@SteveGriffith-Prof3ssorSt3v3]

There is a note in the description about that change to line 50. And the code in the Gist has the correct line. I have another video that should help with the difference between prototype and __proto__ kzbin.info/www/bejne/ZmLNh5p5gJJ7jpY

[@sergeyd9989]

Awesome. You made it clear for me, thank you.

[@cmefindaname]

Gold! Incredible! Thank you!

[@anujkumarjha9454]

hi just wanted to know doesn't it breaks linkage with Function.prototype with EmployeeP ? I guess instead "Object.setPrototypeOf(EmployeeP, PersonP.prototype)" we should use "Object.setPrototypeOf(EmployeeP.prototype, PersonP.prototype)"

[@SteveGriffith-Prof3ssorSt3v3]

That edit is in the description and was changed in the source code in the Gist.

[@TraceguyRune]

is this new? Back in my day, I don't recall JavaScript having classes, much less the ability to extend a class. This is all very Java like.

[@SteveGriffith-Prof3ssorSt3v3]

The "class" and "extend" keywords are only a few years old. But remember that they aren't really classes. They are not like classes in Java. JavaScript really only has the "this" keyword because Brendan Eich, when he created the language, was told that he had to include it and make JS "look" like that other popular 90s language "Java". Brendan did not want to use "new" or "this" in JavaScript because it doesn't use classes. Originally JS was going to be called LiveScript. JavaScript was a marketing thing. Just remember that it is still only "Java like" on the surface.

[@nikhilmalagi9539]

Line no : 50, The setProtoType should be set on EmployeeP's prototype right? Object.setPrototypeOf(EmployeeFun.prototype,PersonFun.prototype) // extends

[@SteveGriffith-Prof3ssorSt3v3]

The code is updated in the gist and there is a note in the description about this.

[@kedarsatwik6938]

What is role of supee(nm,id)

[@maksmephi]

Thanks, it is very helpfull)

[@GeneraluStelaru]

Why is Object.setPrototypeOf necessary? EmployeeP already calls PersonP.

[@SteveGriffith-Prof3ssorSt3v3]

setPrototypeOf is to define the prototype chain. When you create any Object with a constructor function, that function has a prototype object. It is automatically connected with Object.prototype. If you want to define a different prototype chain then you need to connect your own constructor's prototype with the other prototype object, which will then connect with Object.prototype

[@sidarjunful]

After making a connection between the EmployeeP object and the prototype of the PersonP using Object.setPrototypeOf() method, a new prototype method(function) is added on the the EmployeeP object (in the line number 51) with the name of employeeInfo. So, my question is that whether this new method (employeeInfo) will be added to the prototype of PersonP or another prototype object of the EmployeeP? BTW your way of imparting the information (idea) is unmatchable, it's GOLD STANDARD. I will try to teach my students your way.

[@SteveGriffith-Prof3ssorSt3v3]

The new method on line 51 is only being added to the prototype of EmployeeP. With setPrototypeOf on line 50 we are explaining what the next step in the prototype chain will be. If some method is not found inside EmployeeP.prototype then JS will look inside PersonP.prototype. This video also helps my students - kzbin.info/www/bejne/ZmLNh5p5gJJ7jpY

[@longingbydesign]

From what I'm reading, the use of Object.setPrototypeOf() is highly discouraged due to massive performance issues. I also miss how this relates to __proto__ in this very example. Last thing I noticed is that doing SuperClass.call(this, params) is called constructor theft in Nicholas Zakas' excellent book "Principles of object-oriented Javascript", and I wonder if there's any alternatives to that.

[@SteveGriffith-Prof3ssorSt3v3]

Yes. Use Object assign or with the class syntax you can use extends

[@JoseRios-yr6pc]

Thanks a lot! It's much clear now the concept to me

[@stackfulldev]

It should be: Object.setPrototypeOf(EmployeeP.prototype, PersonP.protoype) With code shown in video, you're effectively attaching the employeeInfo() method to PersonP prototype, meaning even PersonP instances would have that method after that point.

[@SteveGriffith-Prof3ssorSt3v3]

Yes. There is a note in the description about that typo. It was fixed in the gist.

[@Cav203]

why arent we able to call - console.log(mary.getDetails()) if the getDetails function was passed to function EmployeeP ?

[@SteveGriffith-Prof3ssorSt3v3]

You can. As long as you changed line 50 to: Object.setPrototypeOf(EmployeeP.prototype, PersonP.prototype); as mentioned in the description. There was a typo in the video.

[@hanenezribi4029]

Grenat tutorial , thanks you

[@sonyniktsol2470]

"vs" sugess that there is any differenc between prototype and class syntax ;/ Give back my 10minutes...

[@SteveGriffith-Prof3ssorSt3v3]

The difference is in the syntax. The point is that it is all prototypes beneath the surface.

[@maitran1764]

At line 47 PersonP.call(this, nm, id) is there any other way to write it using the setPrototypeOf or Object create method? Thank you very much for your tutorial. Amazing as always!

[@SteveGriffith-Prof3ssorSt3v3]

We need to call the PersonP constructor to give us the name and id properties and their values. setPrototypeOf is just creating the prototype chain for inheritance. It is like calling super( ) inside the Class syntax's constructor( ) method.

[@shanglee643]

Why we don't invoke PersonP function inside PersonP right away instead of using PersonP.call()?

[@SteveGriffith-Prof3ssorSt3v3]

Because call( ) or apply( ) let us indicate what value to use for this inside the PersonP function, not relying on the lexical scope.

Great Steve. Cristal clear and you make it easy. But, what happens if you create a variable without new (i.e: let Jose = PersonP)?

[@SteveGriffith-Prof3ssorSt3v3]

Without the keyword new, any function returns whatever is written after the first return keyword in that function. If the function has no return statement then it returns undefined.

[@josbellquiros7055]

Why do you need line 50? Where you set prototype? It seems that you can have inheritance just with the PersonP.call line. I imagine I'm missing some inheritance functionality that would be missing but I can't think of it.

[@SteveGriffith-Prof3ssorSt3v3]

There is a note in the description about a change on line 50. The code was changed in the repo too.

[@tolstoievski4926]

I'm still confused between prototype and the hidden property [[Prototype]] that os called by the accessor function __proto__ ?

[@SteveGriffith-Prof3ssorSt3v3]

There are 3 parts to this. 1. The object. 2. The constructor function that made the object. 3. The prototype object. The function (2) can access the prototype object with the `.prototype` keyword. The object (1) can access the prototype object with the dunder-proto keyword. Here is another video I did on the topic - kzbin.info/www/bejne/ZmLNh5p5gJJ7jpY

[@Richard.halabi]

thanks Steve very helpful.

[@gaborlakatos882]

What happens when you dont put the 'new' keyword there? Im talking about this: let fred = PersonP()

[@SteveGriffith-Prof3ssorSt3v3]

`new` changes the return value of any function - kzbin.info/www/bejne/f2OmlaWBobWXd7s

[@AdrianJDeNiz]

Great video very helpful!

[@belhadjersamir5413]

thank you very much ,you are great

[@chesterxp508]

Another very cool tutorial!

[@masaakistephanebenon547]

very helpful thanks a lot

[@le_Bizarre]

Please make the code as few lines as possible, i got scared from the beginning of the video when I saw that the code is larger than the window, so I got away. This is a shame as I liked the voice.

[@SteveGriffith-Prof3ssorSt3v3]

You never learn if you only look at code that appears easy and safe. Learning comes from struggling and making mistakes.

[@glenottley2823]

What a clear and insightful video on what can be a very complicated concept! I've saved your 'JavaScript from the start' playlist and will be working my way through, one per day. Thanks Steve for the great education!

[@The-cyber-imbiber]

To me, it feels like Typescript interfaces and type aliases can do all the things that you would use classes/prototypes to do. I feel like i might be wrong about this. Does anybody know anything about this?

[@SteveGriffith-Prof3ssorSt3v3]

Typescript is a superset of ECMAScript... which is JavaScript. It just has extra support for things like primitive datatypes that are strongly typed, intefaces, enums, an extra scope level, etc. End of the day it still has JS under the hood with prototypes.

[@Mona001-01g]

You truly deserve a Subscribe. Thank you for breaking down the complexities of a very confusing language!

[@aniketbharsakale2561]

Nice content, nice explanation, I'm a newbie & I could derive a lot of sense out of this. Helpful & v.much to the point. Clean clear crisp. And your voice is so cool :p Cheers keep this great work going.

[@aminehaine3301]

very clear, thank's

[@p3k1n0]

After 10 videos on constructors, classes, and prototypes in javascript, finally a video that makes me really understand....thank you.

[@JeatBunkie]

So happy I found your channel, I could cry! You’re making every subject I was shaky on just make sense!

[@gautamjiart]

Really good explanation

[@seanlynch1841]

This is fantastic. Are there any advantages of one over the other? Maybe private #variables in classes, for example?

[@SteveGriffith-Prof3ssorSt3v3]

It's just two different syntaxes for the same thing. Real #private variables are available in classes but you can mimic them with proper scoping and prototypes.

[@tolstoievski4926]

Why are methods of a class Person store in Person.prototype and after that we call these methods not passing by prototype ?

[@SteveGriffith-Prof3ssorSt3v3]

JavaScript automatically walks up the prototype type chain looking for shared methods and properties. kzbin.info/www/bejne/ZmLNh5p5gJJ7jpY

[@KeplerEmeritus]

Thank you so much for the very concise information. Sometimes I see projects on Github mixing these techniques (Especially Node.js projects). Why is that? Is there some advantage to mixing these or using one or the other?

[@SteveGriffith-Prof3ssorSt3v3]

Classes are just syntactic sugar for prototypes. In the latest updates to classes there are a couple unique things. But for the most part it is a developer preference on how to write the code. Sometimes it will depend on what else they are doing in the code and if it is more functional or more object oriented.

[@KeplerEmeritus]

@@SteveGriffith-Prof3ssorSt3v3 Understood! Thanks so much.

[@MannyGonzalezReyna]

Thank you professor.

[@arashvincent8519]

immeditly subscribed

[@asdfmovie3616]

Brilliant, so concise and easy to understand! Great work! One thing I don't understand is why I"m unable to get details on `employe.getDetails()` unless I set `Object.setPrototypeOf(EmployeeP.prototype, PersonP.prototype)`?

[@SteveGriffith-Prof3ssorSt3v3]

There are two constructor functions Person Employee Each has a prototype object where shared methods for that object type are stored. The getDetails method is inside the prototype for the Person type. So, if you have an object that is of type Employee, it will not have a getDetails method unless you connect the prototype chain to say that Person.prototype is up the chain from Employee.prototype. kzbin.info/www/bejne/ZmLNh5p5gJJ7jpY

[@anupammaurya6624]

Nice explanation 👍

[@millanferende6723]

Can someone explain please? 10:26 How can he pass 3 arguments (this, nm, id) to a function PersonP, that has only 2 properties (nm, id) ?

[@SteveGriffith-Prof3ssorSt3v3]

kzbin.info/www/bejne/q3PHeWOfd5aJeq8

[@millanferende6723]

@@SteveGriffith-Prof3ssorSt3v3 Thank you so much!

[@PankajDas-mw4uq]

By using setprototype method, getDetails method of Person's prototype didn't inherited by EmployeeC. So where is the inheritance now? I wrote the same code in my pc but didn't inherited the method by EmployeeC. Plz explain

[@SteveGriffith-Prof3ssorSt3v3]

Did you get type the code that was on the screen or take the updated version from GitHub? If you typed the version on the screen did you read the note in the description about line 50? With that change, you can add this to the end: console.log(mary.getDetails()); and it works fine.

[@PankajDas-mw4uq]

@@SteveGriffith-Prof3ssorSt3v3 ohhk sir I got it. Thank u

[@kresimircosic3753]

lol insta subbed.

[@sandip_bettereveryday]

Instead of setPrototypeOf we could have also used Object.ceate() right?

[@SteveGriffith-Prof3ssorSt3v3]

Absolutely. Object.create( ) and Object.assign( ) were intended to replace the setPrototypeOf method.

[@sandip_bettereveryday]

@@SteveGriffith-Prof3ssorSt3v3 Thanks for taking time out and replying. Your voice is so assuring.

[@abdouthiam7981]

This is so useful I cannot explain how much it made my learning prototype easy

[@johnacsyen]

Very concise explanation. Better than code bootcamp. Subscribed

[@Cientificosdelsoftware]

Thank you man, you are very talented to explain those concepts... God bless you!

[@Mona001-01g]

When to use class syntax and when to use prototype syntax?

[@SteveGriffith-Prof3ssorSt3v3]

It's all prototypes really. So, there is no performance difference. Just a personal choice as long as you understand how the prototypes are created and used.

[@ShivamMishra-mn6cs]

best explanation

[@nigelbrie5693]

I get back undefined if i replace this with EmployeeP. I don't understand why. @10:06 let EmployeeP = function(nm, id, salary){ PersonP.call(EmployeeP, nm, id); this.salary }

[@SteveGriffith-Prof3ssorSt3v3]

There is a note in the description and in the code gist about a typo on line 50 that needed to be fixed.

[@nigelbrie5693]

@@SteveGriffith-Prof3ssorSt3v3 With the code fix I now get NaN. I'm just confused why I can't substitute "this" for EmployeeP on line 47. Sorry for being noob.

[@SteveGriffith-Prof3ssorSt3v3]

@@nigelbrie5693 Never apologize for learning. Here is another video where I explain about prototype and `this`. kzbin.info/www/bejne/m4iniZqpfsyHfc0 It should help you.

[@AlexDudeOriginal]

the feel when "this" is "undefined" :D:D:DD: (line 41)

[@AlexDudeOriginal]

Wow well nevermind there... cant use arrow functions at that point xD

[@adirbarak5256]

such a good tutorial, you don't skip anything and actually understanding what's a class doing and how to simulate it using prototype explains the logic behind it.

[@funnyanimalworld7579]

is there any difference in which one to use? Perhaps one is faster or something like that? Or are they equal ?

[@SteveGriffith-Prof3ssorSt3v3]

Classes are just a syntactic sugar on top of prototypes. They are equal.

[@funnyanimalworld7579]

@@SteveGriffith-Prof3ssorSt3v3 thank you

[@B-Billy]

Prime level content!! You are really good at JS❤🎉

[@pinakim11]

Thank you so much, you explained it really well.

[@mpc79]

Very well explained. I will be hitting subscribe.

[@HologramJay]

Fantastic explanation. I can always count on this channel to clear things up. Thanks man.

[@kranthikumar5215]

I have never seen a explanation like this really u r a great teacher sir applauds 🙏

[@maniac5411]

Thanks for such clear, and concise concepts! Keep up the good work :)

[@fifilulu]

Hi, great and clear video, thank you. What is the best option in pratice, classes or closures? Which offers the best performance?

[@SteveGriffith-Prof3ssorSt3v3]

In JS, classes and closures are two different things. closures in JS are a built-in feature that allows you to maintain reference to a value that would otherwise have been lost, so that you can use it at a later time. Closures will be used both with objects and prototypes as well as with simple functions and loops. JS classes are a syntactic sugar that lets you define/create Objects and their prototypes with a simplified syntax. As far as performance between classes and older Object.create syntax, there is no real difference. They both create a JS object and a prototype.

[@fifilulu]

@@SteveGriffith-Prof3ssorSt3v3 Thank you for the answer. Sorry, you are right, my question was between classes or prototypes.

[@SteveGriffith-Prof3ssorSt3v3]

@@fifilulu ok. Well the answer is the same. Classes are just syntactic sugar. They create the exact same prototypes behind the scenes . No difference in performance because they are the same thing

[@fifilulu]

@@SteveGriffith-Prof3ssorSt3v3 Interesting, I noticed that most experienced JS developers prefer prototypes. I concluded it was faster, but it is probably because classes have been lately added to the language.

[@SteveGriffith-Prof3ssorSt3v3]

@@fifilulu you will see a lot more of the class syntax when working with React developers. More experienced developers will be more likely to use the older syntax, like you said the class syntax is newer

[@muhammadhossam8557]

one of the best if not the best javascript channels in youtube

[@islombekhasanov]

Perfection

[@russellabraham9208]

Yea one of the nice things about class is its inheritance of scope. Thanks

[@piegpa]

This is such a good explanation, thanks mate.