How to export a class instance in Typescript
Im authoring a TS library, and would like to export an instance of a class, I intend for it be used as singleton in the consuming application.
Right now I have the following structure:
index.ts
export { Foo } from './my-class';
foo.ts
export class Foo {
functionA() {}
}
I'm then building into UMD format using webpack and babel, and in another application (Angular), I am able to import in my class, instantiate it and use it accordingly.
import { Foo } from 'foo';
private foo = new Foo();
const x = foo.functionA();
Is there a way to return an instantiated instance of my class or am I thinking about this the wrong way?
So instead of having to do new Foo(), the imported Foo would actually already be an instance?
Thanks
UPDATE I should have mentioned, I am exporting other things such as interfaces, so I don't think a default class export would be the right way to go correct? - see here
Answer
You can control what you're returning like so:
// Export the named class directly
export class Foo { }
// Export the named class indirectly
class Bar { }
export { Bar }
// Export an instance of the class directly
export const foo = new Foo();
// Export an instance of the class indirectly
const bar = new Bar();
export { bar };
Here's a TypeScript Playground link showing the code compiles and the produced javascript.
The TypeScript Handbook official documentation for exports (and imports, and re-exports): https://www.typescriptlang.org/docs/handbook/modules.html#export
The MDN documentation (courtesy of jo_va): https://developer.mozilla.org/en-US/docs/web/javascript/reference/statements/export
And here's Basarat's guide for them: https://basarat.gitbooks.io/typescript/docs/project/modules.html