How to define Singleton in TypeScript

singleton typescript
maja picture maja · May 11, 2015 · Viewed 104.3k times · Source

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

Alex picture Alex · May 2, 2016

Since TS 2.0, we have the ability to define visibility modifiers on constructors, so now we can do singletons in TypeScript just like we are used to from other languages.

Example given:

class MyClass
{
    private static _instance: MyClass;

    private constructor()
    {
        //...
    }

    public static get Instance()
    {
        // Do you need arguments? Make it a regular static method instead.
        return this._instance || (this._instance = new this());
    }
}

const myClassInstance = MyClass.Instance;

Thank you @Drenai for pointing out that if you write code using the raw compiled javascript you will not have protection against multiple instantiation, as the constraints of TS disappears and the constructor won't be hidden.

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