Generate declaration file with single module in TypeScript not working

Question

The question of how to generate a library with type definitions has been asked before here:

Generate declaration file with single module in TypeScript

The answers says that you just need to set "declaration" to true in tsconfig.json.

I have put together a simple example_library and example_library_consumer projects in this github repo:

https://github.com/jmc420/typescript_examples https://github.com/jmc420/typescript_examples/tree/master/example_library https://github.com/jmc420/typescript_examples/tree/master/example_library_consumer

In example_library I have created an index.ts that exports the class and interface that I want to export:

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

The typescript compiler generates an index.d.ts that is identical to this and doesn't include a module declaration.

I import the library in example_library_consumer in package.json using this dependency:

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

src/ts/index.ts uses the library thus:

import {ILogin, Login} from 'examplelibrary';

let login:ILogin = new Login("[email protected]", "password");

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

Everything compiles ok and the tsc compile generates this:

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
var examplelibrary_1 = require("examplelibrary");
var login = new examplelibrary_1.Login("[email protected]", "password");
console.log("Email " + login.getPassword());

When I run this, I get a runtime error:

var login = new examplelibrary_1.Login("[email protected]", "password");
            ^
TypeError: examplelibrary_1.Login is not a constructor

Most index.d.ts for libraries use the "declare module" and suspect this is the problem. Can the tsc compiler with the declaration flag set to true generate "declare module"?

jmc42 jmc42 · Accepted Answer · 2021-01-19T18:19:22

The problem was with the export:

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

The problem was fixed by changing the export to this:

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

The export default class or interface had to be changed to export class or export interface. You can't export a default class. The Typescript compiler (version 3.9.6) doesn't like this:

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

Generate declaration file with single module in TypeScript not working

1 Answers