Is it possible for me to transfer a change to the worldwide namespace from my library?

Question

Is it possible for me to transfer a change to the worldwide namespace from my library?

I am looking to enhance an existing TypeScript type within the global namespace in my library and then expose it for use in other projects. Can this be done?

Below is my current code:

Promise.ts

Promise.prototype.catchExtension = function<T>(this : Promise<T>): Promise<T> {
    return Promise.prototype.catch.apply(this, [() => { /*do stuff*/ }]);
}

Promise.d.ts

declare global {
    interface Promise<T> {
        catchExtension(): Promise<T>;
    }
}
export { }

How can I utilize this in another application that references my library? Since it was exported without a name using export { }, I cannot use import { .... } from '@mylib'.

typescript

Answer 1

Answer №1

If you want to simply execute the file without importing any specific modules, you can achieve this by using the following code:

import '@mylib'

This will run the file in a separate scope from the module where it is being imported, but it should work without any issues since you are making modifications at the global level.

Answer 2

If you want to simply execute the file without importing any specific modules, you can achieve this by using the following code:

import '@mylib'

This will run the file in a separate scope from the module where it is being imported, but it should work without any issues since you are making modifications at the global level.

Answer 3

Answer №2

After some experimentation, I have finally discovered a solution to the problem. I am sharing it here in case it can help others as well.

The key was to include both the declaration and definition in the .ts file and then import the file (anywhere!) in the library. This allowed my other project to access the extension method as soon as it imported anything from the library.

Here is the updated code:

Within the library project:

Promise.ts

Promise.prototype.catchExtension = function<T>(this : Promise<T>): Promise<T> {
    return Promise.prototype.catch.apply(this, [() => { /*do stuff*/ }]);
}

declare global {
    interface Promise<T> {
        catchExtension(): Promise<T>;
    }
}
export { }

lib.ts

import './Promise'; // this line can be placed in any file within the library...
export { } from './Promise';
// Additional exports
export { Example } from './Example';

Within the main app:

// Import anything from the library
import { Example } from '@mylib';

const x: Promise<string> = new Promise( (resolve, reject) => { reject(); });
x.catchExtension();
// The extension method works as expected

Answer 4

After some experimentation, I have finally discovered a solution to the problem. I am sharing it here in case it can help others as well.

The key was to include both the declaration and definition in the .ts file and then import the file (anywhere!) in the library. This allowed my other project to access the extension method as soon as it imported anything from the library.

Here is the updated code:

Within the library project:

Promise.ts

Promise.prototype.catchExtension = function<T>(this : Promise<T>): Promise<T> {
    return Promise.prototype.catch.apply(this, [() => { /*do stuff*/ }]);
}

declare global {
    interface Promise<T> {
        catchExtension(): Promise<T>;
    }
}
export { }

lib.ts

import './Promise'; // this line can be placed in any file within the library...
export { } from './Promise';
// Additional exports
export { Example } from './Example';

Within the main app:

// Import anything from the library
import { Example } from '@mylib';

const x: Promise<string> = new Promise( (resolve, reject) => { reject(); });
x.catchExtension();
// The extension method works as expected

Is it possible for me to transfer a change to the worldwide namespace from my library?

Answer №1

Answer №2

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