Instance of exported class declared in Typescript

Currently, I am in the process of developing my initial declaration file for a foreign library known as react-native-background-timer. Within this library, there exists a default export that I am uncertain about how to declare within the index.d.ts file.

This is the default export found in the library:

export default new BackgroundTimer();

While I understand how to declare exported classes, I am unsure of the best method to declare an exported class instance.

Initially, my approach was as follows:

declare class BackgroundTimer {
    [...]
}

declare const _BackgroundTimer: BackgroundTimer;
export default _BackgroundTimer;

Answer №1

Indeed, this method of declaring a default export that exports an instance is the correct approach. This change was outlined on the TypeScript 2.6 breaking changes page, which you can visit by following this link. In the past, it was feasible to achieve this in just one line within the declaration file as shown in the code snippet below:

export default new BackgroundTimer();

However, the capability to include arbitrary expressions within the export statement has since been restricted.

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