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);

ts-類和繼承