Typescript: Allow "this.constructor" in a constructor before super

Created on 22 Mar 2019 · 5Comments · Source: microsoft/TypeScript

What I want to be able to do is ultimately have access to the class inside a constructor. Accessing this.constructor should be safe (I think?), and would allow for sub-classes to call their own static methods before calling the super:

class BaseProvider {
    constructor(url: string) { ... };
}

abstract class GenericProvider {
    constructor(something: any) {
        let url = this.constructor.getUrl(something);
        super(url);
    }
    static getUrl(something: any): string {
        throw new Error("subclass must implement this");
    }
}

class SpecificProvider {
    // This class does not need to override the constructor, just the static method

    static getUrl(something: any): string {
        return "https://helloworld"
    }
}

I have not been able to find a way to get around this, but if it already exists, awesome. Otherwise, this would go a long way to improving the use of static methods in TypeScript, and a the standard way to handle things like this.

Thanks!

Source

ricmoo

All 5 comments

It's a ReferenceError to reference this in the constructor of a derived class before calling super().
This has been that way since the introduction of classes in ES6