Issues with TypeScript types

[joshkel]

We're having some issues with the type definitions for chartjs-plugin-zoom. Are the Types Wrong is reporting the following issues:

"chartjs-plugin-zoom"
node10	❗️ Incorrect default export
node16 (from CJS)	❗️ Incorrect default export
node16 (from ESM)	❗️ Incorrect default export🕵️ Named exports
bundler	❗️ Incorrect default export

This is causing problems for my project when I set my project's tsconfig.json to "module": "nodenext", "moduleResolution": "nodenext". For example:

import type ZoomPlugin from 'chartjs-plugin-zoom';

const scale = makeMyCustomScale();

function registerZoomFunctions(zoom: ZoomPlugin) {
  zoom.zoomFunctions[scale.id] = () => false;
}

error TS2339: Property 'zoomRectFunctions' does not exist on type 'typeof import("/Users/josh/src/app/node_modules/chartjs-plugin-zoom/types/index")'.

While investigating this, I also saw that the TypeScript port in master doesn't have functioning types at all: it specifies dist/index.d.ts, but that file doesn't exist. As I understand it, the correct solution would be to use rollup-plugin-dts or similar to combine the individual .d.ts files into a single .d.ts file under dist (matching the single .js file under dist) and to create separate .d.ts files for the CJS and ESM builds.

As I understand it, the problem is because a "true" CommonJS default export (as Rollup does by default when it can, and as represented in a TypeScript .d.ts by export = ZoomPlugin) is different than a CJS-ESM-interop default export (which is something like exports.default = ZoomPlugin; Object.defineProperty(exports, '__esModule', { value: true }); and is represented by a TypeScript .d.ts as export default ZoomPlugin). I haven't found a good solution to this; I wonder if the simplest fix is to change Rollup to use named exports for its CJS build (and maybe even separate the CJS and UMD builds, as Chart.js itself does, to make this a little more explicit).

See chartjs/chartjs-plugin-annotation#978 for where I'm working on a similar set of changes for chartjs-plugin-annotation. If you'd like for me to do something similar here, please let me know.