08-classes.ts

//  Lets create a class that represents a vehicle.
//  we use the class keyword followed by class name.
// We capitalise first character in name as per convention

//  Lets add a method drive that just prints to console, attotate it as no argument and retun type void
class Vehicle {
  drive(): void {
    console.log('speed is good');
  }

  honk(): void {
    console.log('Beep beep');
  }
}

// Like we saw in README.md, class is just a blue print or definition of what a vehicle should be.
// We generally dont call the method attached to class directly
// In some cases we can but with normal methods we do not.
// Instead we use the class to create an instance (object)
//  We use the new keyword to to create an instance of the class
//  As convention you will see sometimes the instance also has same name but lowercase like so
const vehicle = new Vehicle();

//  Now vehicle instance has access to drive method that was in class
vehicle.drive();

// Now if you run this file you will see the output Speed is good.
// In the terminal
// change to current directory with this file using cd command $cd 02_ts_features
// $ ts-node 08-classes.ts

//  You can lo have as many methods as you want in class. lets go back and add a method honk in class and call it with instance

vehicle.honk();

//  Now if yoy run it with ts-node you will see both 'speed is good' and 'beep beep'

//  Now lets talk a bit about inhereitence, lets create a class called Car. Think about how Vehicle and car are related in real world
//  We could say that Car is a type of Vehicle?
//  so what ever a car could do a vehicle should be able to do as well.
//  So we would want class Car to have all the methods same as Vehicle
//  To achieve this Car class can extend the Vehicle class

class Car extends Vehicle {
  drive(): void {
    console.log('Vrooom!');
  }
}

//  Now if we create an istance of Car class we can still call the drive and honk methods

const bmw = new Car();

bmw.drive();
bmw.honk();

//  when we extend a class from another class we have the option to override methods.
//  Lets say in our case we want Car class to have a different implementation of drive method

//  To do so we can go back and simply redefine the drive method inside of Car class