How to define Singleton in TypeScript

Question

What is the best and most convenient way to implement a Singleton pattern for a class in TypeScript? (Both with and without lazy initialisation).

Answer 1

Here is yet another way to do it with a more conventional javascript approach using an IFFE:

module App.Counter {
    export var Instance = (() => {
        var i = 0;
        return {
            increment: (): void => {
                i++;
            },
            getCount: (): number => {
                return i;
            }
        }
    })();
}

module App {
    export function countStuff() {
        App.Counter.Instance.increment();
        App.Counter.Instance.increment();
        alert(App.Counter.Instance.getCount());
    }
}

App.countStuff();

View a demo