Create a Static Class in Typescript

You can't have static classes in Typescript out of the box, but there are several approaches to make a class that cannot be instantiated. This article is about them.

1. Make constructor private

class JustAClass {
  private constructor() { }
}

Intellisense will alert if you try to instantiate it.

2. Throw error in class constructor

class Static {
  constructor() {
    throw new Error('No, you don\'t!');
  }
}

Throwing an error inside the constructor gets the job done, moreover other classes can now inherit this one to become static themselves:

class JustAClass extends Static {
  constructor() { super(); }
}

Though no intellisense to help unlike in the first way.

3. Use abstract instead

abstract class JustAClass {}

Intellisense is still going to alert you when trying to instantiate it, though it looks like a misuse of the abstract keyword.

4. Create a decorator to make any class static

This approach combines method 2 with typescript's decorators feature. We create a function that pumps out anonymous class which inherits a given class, and overrides its constructor call with throwing an error. And yes, it breaks all the rules and does not call the super like a bad boi, so we silence the compiler with @ts-ignore.

function Static<T extends new (...args: any[]) => any>(ctr: T): T {
  return class extends ctr {
    // @ts-ignore
    constructor(...args: any[]) {
      throw new Error('no way dude');
    }
  }
}

@Static
class JustAClass {}

While not providing the safety of intellisense, this approach is quite declarative.

That's the four ways I discovered :)