Typescript error “An export assignment cannot be used in a module with other exported elements.” while extending typescript definitions

Question

I have downloaded the type definition of a module, let\'s say ModuleA, from @types/module-a.

The module-a.d.ts file lo

Answer 1

I found that I could combine export = syntax with namespace to export types from the interface. export = is necessary (as far as I understand) to indicate that an external module uses CommonJS-style exports rather than ES6 exports. If you try to both use export = and export in the same module, you will receive the following error:

TS2309: An export assignment cannot be used in a module with other exported elements.

However, if you declare a declare a namespace with the same name as the variable used in the exports = expression, you can place types inside of that namespace, making them accessible to consuming modules.

Here is an example of a module type definition using this technique:

declare module 'some-module' {
  namespace SomeClass {
    export interface IMyInterface {
      x:string;
    };
  }
  class SomeClass {
    constructor(p:SomeClass.IMyInterface);
  }
  export = SomeClass;
}