javascript basics - V

javascript basics - using prototype for inheritance, abstract classes

by deshpandeakhil

JavaScript

var f = function(arg) {
    if (arg != null) {
        document.write(arg);
        document.write("<br/>");
    } else if (arg == undefined) {
        document.write("undefined<br/>");
    }
    else {
        document.write("<br/>");
    }
};

//inheritance
//base class
function Vehicle(vType){
    this.vType = vType;
    Vehicle.prototype.displayType = function(){f(this.vType);};
};
//instance class
function Car(color,brand){
    this.color = color;
    this.brand = brand;
};
//setting baseclass to protoype property
Car.prototype = new Vehicle("Four wheeler");

var v = new Vehicle("None");
v.displayType(); 
var c = new Car("black","lotus");
c.displayType();f(c instanceof Vehicle);f(c instanceof Car);

//abstract class
//its kinda abstract because we cant instantiate it via new VehicleAbs()
var VehicleAbs = {
    vType: "None",
    displayType: function(){f(this.vType);}
};
//instance class
function Bike(color, brand){
    this.color = color;
    this.brand = brand;
    this.vType = "Two Wheeler";
};
//setting baseclass to prototype property
Bike.prototype = VehicleAbs;

var b = new Bike("black", "Ducati");
b.displayType();
//f(b instanceof VehicleAbs); this will throw error
f(b instanceof Bike);