class Counter {
    private static instance: Counter;
    private static count: number = 0;

    private constructor() { }

    public static getInstance(): Counter {
        if (!Counter.instance) {
            Counter.instance = new Counter();
        }

        return Counter.instance;
    }

    public getCount(): number {
        return Counter.count;
    }

    public increment(): void {
        Counter.count++;
    }
}

function clientCode() {
    const s1 = Counter.getInstance();
    const s2 = Counter.getInstance();

    if (s1 !== s2) throw new Error('Singleton doesnt work');

    s1.increment();
    console.log('s1:', s1.getCount());
    console.log('s2:', s2.getCount());
}

clientCode();