Using Typescript: Passing the name of a subclass as a parameter to a function

Below is the simplified code snippet that I am working with:

class Component {

}

class CameraComponent extends Component {
    foo: number;

    constructor(bar: number) {
        super()
    }
}

function doSomething(klass: typeof Component) {

}

doSomething(CameraComponent);

Encountering the error message:

TS2345: Argument of type 'typeof CameraComponent' is not assignable to parameter of type 'typeof Component'.

To resolve this error, I made a modification to CameraComponent as shown below:

class CameraComponent extends Component {
    foo: number;

    constructor() {
        super()
    }
}

I'm curious about why changing the constructor signature fixed the issue. Is there any other way to address this problem without using any?

Answer №1

Contained within the definition of typeof Component is not just the information that klass is a constructor required to return a Component, but also details regarding the parameters expected by that constructor. Therefore, attempting to pass in a CameraComponent with a different number of parameters will result in an error

If you wish to allow any constructor that produces a Component, you can utilize

new (...a: any[]) => Component

class Component {

}

class CameraComponent extends Component {
    foo: number;

    constructor(bar: number) {
        super()
    }
}

function performAction(klass: new (...a: any[]) => Component) {

}

performAction(CameraComponent);

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