Polymorphism in Typescript

However TypeScript end result is Plain JavaScript, we can only provide the single method block. Through the use of conditional statements;

class Car{
    setSpeed(message: string);
    setSpeed(message: number);
    setSpeed(message: boolean);
    setSpeed(message: any) {
        if (typeof message === "string") {
            alert(message);
        } else if (typeof message === "number") {
            alert("The number provided was: " + message);
        } else if (typeof message === "boolean") {
            alert("The boolean value was: " + message);
        } else {
            alert(message);
        }
    }
}

var car = new Car();
car.setSpeed(false);