Trouble creating a declaration file for a single TypeScript module

Here is a question that has been previously asked: How can a library with type definitions be generated? The answers provided suggest simply setting "declaration" to true in the tsconfig.json file.

For an example of this concept, I have created both example_library and example_library_consumer projects within this GitHub repository:

https://github.com/jmc420/typescript_examples

In the example_library project, I have created an index.ts file that exports specific classes and interfaces:

export * from './ILogin';
export * from './Login';

However, upon compiling, the TypeScript compiler generates an index.d.ts file without including a module declaration.

The library is imported into the example_library_consumer using the following dependency in the package.json file:

"examplelibrary": "file:../example_library"

In the source code (src/ts/index.ts), the library is used as follows:

import {ILogin, Login} from 'examplelibrary';

let login:ILogin = new Login("email@example.com", "password");

console.log("Email "+login.getPassword());

Despite successful compilation, a runtime error occurs when running the code:

var login = new examplelibrary_1.Login("email@example.com", "password");
            ^
TypeError: examplelibrary_1.Login is not a constructor

This issue may stem from the absence of a "declare module" statement typically present in index.d.ts files for libraries. Can the tsc compiler generate this "declare module" line with the declaration flag set to true?

Answer №1

An issue arose with the export mechanism:

export * from './ILogin';
export * from './Login';

To resolve the problem, the export was revised to:

export {ILogin} from './ILogin';
export {Login} from './Login';

The default class or interface export had to be modified to an explicit class or interface export. Exporting a default class is not allowed. The Typescript compiler (version 3.9.6) raised errors for the following syntax:

export ILogin from './ILogin';
export Login from './Login';

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