JS Tutorials
JS Introduction
JS Syntax
JS Comments
JS Variables
JS Operators
JS Data Types
JS Functions
JS Objects
JS Numbers
JS Arrays
JS Array Methods
JS Booleans
JS Events
JS Strings
JS Dates
JS Maths
JS Objects
Object Definition
Object Properties
Object Methods
Object Display
Object Prototypes
Object Iterables
Object Sets
Object Maps
Object References
JS Functions
Function Definition
Function Parameters
Function Invocation
Function Call
Function Apply
Function ClosuresJS Classes
Class Intro
Class Inhertitance
Class Static
JS Async
JS Callbacks
JS Aysnchronous
JS Prmosies
JS ASync/Await
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Class Inheritance
To create a class inheritance, use the extends
keyword.
A class created with a class inheritance inherits all the methods from another class:
Example
Create a class named "Model" which will inherit the methods from the "Car" class:
constructor(brand) {
this.carname = brand;
}
present() {
return 'I have a ' + this.carname;
}
}
class Model extends Car {
constructor(brand, mod) {
super(brand);
this.model = mod;
}
show() {
return this.present() + ', it is a ' + this.model;
}
}
let myCar = new Model("Ford", "Mustang");
document.getElementById("demo").innerHTML = myCar.show();
The super() method refers to the parent
class.
By calling the super() method in the
constructor method, we call the parent's constructor method and gets access to
the parent's properties and methods.
Inheritance is useful for code reusability: reuse properties and methods of an existing class when you create a new class.
Getters and Setters
Classes also allows you to use getters and setters.
It can be smart to use getters and setters for your properties, especially if you want to do something special with the value before returning them, or before you set them.
To add getters and setters in the class, use the
get and set keywords.
Example
Create a getter and a setter for the "carname" property:
constructor(brand) {
this.carname = brand;
}
get cnam() {
return this.carname;
}
set cnam(x) {
this.carname = x;
}
}
let myCar = new Car("Ford");
document.getElementById("demo").innerHTML = myCar.cnam;