/javascript-classes-complete-guide/ about dmitripavlutin.com-comments HOT 14 OPEN

look! I find one:

class Pet {
  constructor(sound) {
    this.sound = sound;
  }
}
class Dog extends Pet { 
	constructor (sound){
    super(sound);
  }
}
const aDog = new Dog('au') ;
aDog instanceof Dog ; //-> true
aDog instanceof Pet ; //-> true

Object.getPrototypeOf( Dog ) ; //-> class Pet
const aPet = new (Object.getPrototypeOf( Dog ))

aPet instanceof Dog ; //-> false
aPet instanceof Pet ; //-> true

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Great post as always.

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Comment written by Felix Sanz on 01/16/2020 17:37:32

I don't understand the example in section 5.2. Can't you just do if (this.name === '') { ?? If the property is inherited, why calling super on the method?

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Comment written by Dmitri Pavlutin on 01/16/2020 19:29:56

The chapter explains the method overriding.

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Comment written by Felix Sanz on 01/16/2020 20:31:54

But your example is not overriding nothing at all because the inherited method is so dummy, right? It would make more sense if the parent method contains some code, not just return the property (because the property was accesible without calling super on the method anyway). I'm right?

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Comment written by Dmitri Pavlutin on 01/16/2020 20:45:04

The method overriding enhances the parent method (simple or not it does not matter) by providing a default value if the returned value is an empty string.
That’s a simple demo, don’t expect enterprise level code. 😜

Anyways, if you know a better sample, feel free to create a pull request for the post.

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Comment written by igor thetigor on 02/17/2020 23:56:37

Dmitri, thank you so much for all your posts. Really good work, absolutely worthwhile. props!

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Comment written by Dmitri Pavlutin on 02/18/2020 08:36:03

Thanks!

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Comment written by Nayaka Yoga Pradipta on 07/29/2020 13:54:40

Thank you so much. Your article is easy to understand!
But do you have reference small project example that uses JS class?

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Comment written by Dagg on 10/14/2020 21:20:39

Class is actually a function, it is a syntactic sugar for a function constructor. And function constructor is a way to generate objects.

Prototypal inheritance is something different, it creates object literals via Object.create() from another object that acts as a prototype of a newly created object. So class is not generated via prototypal inheritance. Thanks

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So, how should a class method be added after the class declaration?

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Thanks for this great article. I miss two methods in this guide that may not yet exist in JavaScript. First a method that answers how many subclasses a class has. Second, the opposite: a method that reports what the superclass is.
Example:

class Foo(object): pass
class Bar(Foo): pass
class Baz(Foo): pass
class Bing(Bar): pass
print([cls.__name__ for cls in Foo.__subclasses__()])
# ['Bar', 'Baz']
for cls in Foo.__subclasses__():
    print(cls.__base__)
# <class '__main__.Foo'>
# <class '__main__.Foo'>

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Thanks for this great article.

@meetsCode You're welcome! 😄

I miss two methods in this guide that may not yet exist in JavaScript. First a method that answers how many subclasses a class has. Second, the opposite: a method that reports what the superclass is.

This can be useful, however, I'd rather not include these into the post.

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Hi, can you please provide cases where private fields are useful?
The second question, if I create a page object model (not on Cypress) does it make sense to use private fields to protect selectors?

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