classes.ts

class Greeter {
  greeting: string;
  constructor(message: string) {
    this.greeting = message;
  }
  greet() {
    return 'Hello, ' + this.greeting;
  }
}

let greeter = new Greeter('world');

///////////////////////////////////////////////////////////////////////////

class Animal {
  name: string;
  constructor(theName: string) {
    this.name = theName;
  }
  move(distanceInMeters: number = 0) {
    console.log(`${this.name} moved ${distanceInMeters}m.`);
  }
}

class Snake extends Animal {
  constructor(name: string) {
    super(name);
  }
  move(distanceInMeters = 5) {
    console.log('Slithering...');
    super.move(distanceInMeters);
  }
}

class Horse extends Animal {
  constructor(name: string) {
    super(name);
  }
  move(distanceInMeters = 45) {
    console.log('Galloping...');
    super.move(distanceInMeters);
  }
}

let sam = new Snake('Sammy the Python');
let tom: Animal = new Horse('Tommy the Palomino');

sam.move();
tom.move(34);

///////////////////////////////////////////////////////////////////////////

class Person {
  protected name: string;
  constructor(name: string) {
    this.name = name;
  }
}

class Employee extends Person {
  private department: string;

  constructor(name: string, department: string) {
    super(name);
    this.department = department;
  }

  public getElevatorPitch() {
    return `Hello, my name is ${this.name} and I work in ${this.department}.`;
  }
}

let howard = new Employee('Howard', 'Sales');
console.log(howard.getElevatorPitch());
console.log(howard.name); // error

///////////////////////////////////////////////////////////////////////////

let passcode = 'secret passcode 2';

class Employee2 {
  private _fullName: string;

  constructor(_fullname: string) {
    this._fullName = _fullname;
  }

  get fullName(): string {
    return this._fullName;
  }

  set fullName(newName: string) {
    if (passcode && passcode == 'secret passcode') {
      this._fullName = newName;
    } else {
      console.log('Error: Unauthorized update of employee!');
    }
  }
}

let employee = new Employee2('Bad Name');
employee.fullName = 'Bob Smith';
if (employee.fullName) {
  console.log(employee.fullName);
}