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Hello, guys.

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Good to see you back once again.

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I'm back with another tutorial related to object oriented programming in JavaScript.

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And in this lesson we are going to learn about inheritance.

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Now the question is what is inheritance?

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In our previous tutorial, we learn a lot about classes, how we can create constructors, how we can

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create property in class with that.

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Also, we learn how we can create object using class.

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And now we are going to learn about inheritance.

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Suppose I create a class and our class name is a and this class have its own property and methods.

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At the same way we have another class and our another class name is class B.

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It is also have its own property and methods.

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Now the question is can we use class property and method from class B?

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No we can.

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We cannot use class A properties and methods in a simple way.

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For that we need to use inheritance.

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Inheritance is going to allow us to do it.

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Suppose if I want to access class properties and method from class B, in that case class A become base

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class and the class who are going to use base class property is called the right class.

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Not only that, we can create another derived class which is class C.

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Now class C can able to use class B properties and method.

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Also class A properties and method.

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This is the single level inheritance and this is called multi level inheritance because class C derived

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with class B also class A.

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I know it's look pretty confusing for you.

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Let me give you the real life and graphical example.

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Inheritance.

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Allow us to define a class that inherits all the methods and properties from another class.

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Now let's try to understand it in a simpler terms with a picture.

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Suppose this is your grandfather, and your grandfather owned a lot of land in the past.

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So at object oriented term, we can call your grandfather grandparent class.

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And then he decided to give all the lands to his son.

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Means your father.

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I want to say your father get property from your grandfather.

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But your father himself owned a lot of properties.

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Your father bought many shares.

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So your father now owns two type of properties.

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So he can sell his land and his own shares if he wish.

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But your father decide to transfer his ancestral property and shares to your name.

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But you yourself have made a lot of properties.

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You have lot of cryptocurrencies.

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So if you want, you can use your own cryptocurrency.

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Otherwise your father shares.

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Otherwise your grandfather lands, but your grandfather cannot use your father.

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Share.

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Also, your father cannot use your cryptocurrencies, but your father can use his father lands.

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But your grandfather is not authorized to use his son's shares.

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Similarly, your father cannot use your cryptocurrencies, but you have to access all of it.

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You can use land, you can use shares, and also you can use your own cryptocurrencies.

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Basically we control repeatability using inheritance.

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Now let's understand it with object oriented term.

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Suppose your grandfather land is a function and your father share is also function.

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So you don't need to type both the function in your child class.

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You can access it when you want, but your grandfather and your father cannot access your properties.

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I hope now it's clear for you what is inheritance?

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I have tried to explain you in a very simple way.

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Now let me show you this syntax.

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How it works.

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Suppose I have a class which is fruits.

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And now I want to create another class which is able to use class fruits properties and method.

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And our class name is vegetables which is extended with fruit class.

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So in our case base class is fruits and vegetable is the right class which is derived with fruits.

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And here we need to use a special keyword which is used to derive it with another class.

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And the keyword is extends.

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Next we need to pass the base class name.

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And in our fruit class we have some properties and methods.

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Then create a object using fruit class.

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Let f equal to new fruits.

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So f is our object and this object is able to use only fruit class property and methods.

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But if I create an object using vegetable class, suppose let v equal to new vegetable.

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Then this object can access its own properties and methods.

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Also it can access fruit class properties and methods.

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So this is how inheritance work.

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So let's start the practical and see how we can use it.