Inheritance in Javascript (ES6)

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INHERITANCE :

The extends keyword is used in class declarations or class expressions to create a class which is a child of another class.

 
class ChildClass extends ParentClass { ... }
The extends keyword can be used to subclass custom classes as well as built-in objects. The .prototype of the extension must be an Object or null.


Examples : - 

Using extends - 


Please click on this link  https://googlechrome.github.io/samples/classes-es6/index.html for a better example.

Using extends with built-in objects - 


class myDate extends Date {
  constructor() {
    super();
  }

  getFormattedDate() {
    var months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];
    return this.getDate() + '-' + months[this.getMonth()] + '-' + this.getFullYear();
  }
}


Extending null

Extending from null works like with a normal class, except that the prototype object does not inherit from Object.prototype.
class nullExtends extends null {
  constructor() {}
}

Object.getPrototypeOf(nullExtends); // Function.prototype
Object.getPrototypeOf(nullExtends.prototype) // null

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