javaScript's - inheritance, super keyword, new keyword

JavaScript’s (OOJS)





Today’s topic - Inheritance, Super keyword, New keyword.


Inheritance - 

Inheritance basically means to create a child class which has access to a parent class or base class. The child class inherits all the methods from its parent class. 

To create a class inheritance we use the Extends keyword.

Inheritance is basically great for code reusability. 

WHY?

Because  you can use the properties and methods of the parent class in the child class.


Super keyword - 

So basically the super() keyword is only available to classes. The super() always refers to the parent class constructor.

By calling the super() method in the constructor of the child class you call the parent class constructor and get access to parent properties and methods.

If there is a constructor in the child class the super() method should be used before this() keyword otherwise it will cause a reference error.


New keyword - 

The new keyword is basically used to create an instance of an object through a constructor method.

The new keyword does the following things behind the scenes.

  • Creates a new object.

  • Sets the prototype (__proto__) of this newly created object as same as the constructor function’s prototype.

  • Binds this keyword with the newly created object and executes the constructor function.

  • Returns a newly created object.

Eg - Inheritance,  super,  new.


Hoisting - 

Hoisting is basically that the javaScipt goes through code code before executing it and stores all the function declarations in the memory. So it allows you to use the function before their declaration in your code.

But it is not the same with classes. Hoisting is not available for classes you cannot use a class before it’s declaration. And if you do you know you’ll get your favorite thing an “ERROR” yup!



Summary

  • Inheritance means using functionality of the base class in the derived class by using the extend keyword.

  • super() keyword is used to call the parent constructor method and get access to its properties and method in derived class.

  • New keyword is used to create an object from the constructor function.

  • Hoisting means that the functions can be used before their declaration but it’s not the same with the classes.


That's all for today, Hope you learned something.

have a beautiful day ❤



ps - me finding the error's origin for about 3 hours and finding out it is just the freaking ( ; ) missing.

Comments

Post a Comment

Popular posts from this blog

JavaScript - Arrays

Image
  JavaScript Arrays Today’s topic JavaScript arrays and some of its most used methods. What are Arrays ?  Arrays re used to store more than one value at a time Arrays are special variables.  Syntax: const array_name = [ n 0 , n 1 , n 2 , n 3 , n n ]; Eg: This is the basic way for creating an array.  Types of arrays (1) Uniform -  An array which has a single type of data. Eg - Uniform array. (2) Un uniform - An array which has multiple types of data. Eg - Un uniform array. (2) Dimensional Array - A simple description would be the 2D Array are Arrays of Arrays.  Eg - 2D array. The Array.from( ) :   It takes an array-like object & turns it into a complete array, or you can say does a shallow copy. In which you can perform all array functions.  Syntax : Array from (arrayLike, mapfn, thisarg)  arrayLike An array-like or iterable object to convert to an array . mapFn Optional Map function to call on every element of the array . thisArg ...
Read more

javascript's - this keyword, getters & setters, Dom box dimension properties

Image
  JavaScript Today’s topic - this keyword, Getters & Setters,  Dom box dimension properties. This keyword this keyword’s  simple description would be it refers to the object in which it is used. this can give different values based on where it has been used. Global context - In global context  i.e used outside of any function this will refer to the global object. this in a global context. Function context - When this keyword is used in the function in non strict mode this will refer to the global object . this in a function context. Function context (“strict mode”) - When  this keyword is used in the function context in strict mode this will be undefined. this in a function context using strict mode. Method context - While used in method context this refers to the owner of the method in which it is used. this in a method context. Event context -   When used in an event context this will refer to the element by which the event is called. this...
Read more