JavaScript: プロパティへの値代入時の処理を変更する

defineProperty.ts

class Greeter {
    constructor(private _greeting: string) {
    }
    get greeting() {
        return this._greeting;
    }
    set greeting(value: string) {
        this._greeting = value;
    }
}

let greeter = new Greeter("Hello, world");

const prop = 'greeting';
const real = Object.getOwnPropertyDescriptor(Greeter.prototype, prop);
console.log(real);

Object.defineProperty(greeter, prop, {
    get: () => real.get(),
    set: value => {
        real.set(value);
        console.log('success');
    },
    enumerable: real.enumerable,
    configurable: real.configurable
});

let button = document.createElement('button');
button.textContent = "Say Hello";
button.onclick = function () {
    greeter.greeting = 'test';
    alert(greeter.greeting);
}

document.body.appendChild(button);