How to implement Singleton in Typescript?

Here is an example of how we implement Singleton in Typescript

/**
 * The Singleton class defines an `instance` getter, that lets clients access
 * the unique singleton instance.
 */
class Singleton {
    static #instance: Singleton;

    /**
     * The Singleton's constructor should always be private to prevent direct
     * construction calls with the `new` operator.
     */
    private constructor() { }

    /**
     * The static getter that controls access to the singleton instance.
     *
     * This implementation allows you to extend the Singleton class while
     * keeping just one instance of each subclass around.
     */
    public static get instance(): Singleton {
        if (!Singleton.#instance) {
            Singleton.#instance = new Singleton();
        }

        return Singleton.#instance;
    }

    /**
     * Finally, any singleton can define some business logic, which can be
     * executed on its instance.
     */
    public someBusinessLogic() {
        // ...
    }
}

Above example is standard way to implement Singleton but it is not safe when working with multiple threads

For thread safe we can use a lock mechanism when getting instance of Singleton