Object Oriented Programming in JavaScript

oop-exp.js

/*** OOP in JS ***/

// No Classes in JavaScript, but constructor functions.

var a = 5; 
// is equivalent to calling  
var a = Number(5); // JavaScript abstracts it.
// Number is a Constructor Function

// A Class. First letter caps only for symantics
function Vehicle(type, make) () {
    this.type = type;
    this.make = make;
}

var car = new Vehicle('four-wheeler', 'Honda');
// The prototype of Vehicle function is copied to car, in car's context
// Hence prototypal inheritance

var car2 = new Vehicle('two-wheeler', 'TVS');

Vehicle.prototpe.candrive = true;
// "prototype" property is available only to functions
// Modifying them would propogate to all instantiated objects, past, present and in future!

car.candrive; // true; prototypal chain is queried from bottom to top
car2.candrive; // true; "true" comes from the prototype

/*** Level 2 Inheritance:
 Child Class inheriting from Parent Class ***/

function Vehicle(){
    // allocated properties
}

Vehicle.prototype.properties... // Static
Vehicle.prototype.methods ...

function SpaceJet(){
    Vehicle.apply(this, args); // args = arguments whatsoever
}

SpaceJet.prototype = new Vehicle();
// prototype is always an object
// here it is going to be copied to all SpaceJets
// Above code inherits properties and methods from Vehicle's prototype.

SpaceJet.prototype.constructor = SpaceJet; // Hardcoding required in JavaScript
// Because only we know its SpaceJet prototype, but for JavaScript,
// ... its just an Object that came from calling Vehicle constructor.

// Overriding
SpaceJet.prototype.candrive = false
// Adding new methods
SpaceJet.prototype.fly = function() {
   // ...
}

// Objects
var myJet = new SpaceJet("params");
// Custom property only to this object
myJet.name = 'Chrome Jet';

myJet.fly();

/***
 * UPDATE
 **/

// Private variables are achieved through IIFE, which are self executing:

var jet = ( function() {
    // Private
    var wings = 5,
        canfly = true;

    return {
        // Public
        getWings: function() {
            return wings;
        }
        // ...
    }
}());

jet.getWings();