elchininet / rollup-plugin-dts-issue

Small repo to demonstrate an issue with options in rollup-plugin-dts plugin

rollup-plugin-dts-issue

How to reproduce the issue:

• Clone this repo
• Run yarn
• Run yarn build
• Run yarn build-dts

Inspect the folder dist. The content of the index.js cjs module will be:

'use strict';

function square(n) {
    return n * n;
}

module.exports = square;

The content of the indx.d.ts file will be:

declare function square(n: number): number;

export { square as default };

So, the output options format and exports have been ignored in the rollup.dts.config.js file.

This provokes that importing the module in commonjs, TypeScript expects a named default, check the typescript-error.js file to check what TypeScript says in the call to square(3):

This expression is not callable. Type 'typeof import("rollup-plugin-dts/dist/index")' has no call signatures.ts(2349)

Changing the first line to const square = require('./dist').default; solves the TypeScript error but then the code will fail because the module doesn‘t have any default, the function has been exported using module.exports = square.