Fix default exports

[GalMunGral]

Context

Trying to port the examples to TypeScript produces the following errors:

It turns out that default exports are misused in many places in the .d.ts files:

1. Since the original .js files don’t have types, default exports should always be values. But in some cases, an interface declaration is incorrectly assigned as the default export, rather than a value that conforms to that interface. This leads to the error shown in the screenshot.
2. Most files correctly default-export a value and separately export the interface type as a named export. However, other .d.ts files mistakenly use the default import syntax to import interfaces — which resolves to the exported const values instead of the type definitions.

Results

The type errors related to default exports are resolved.

Changes

• Changed import/export statements in in multiple .d.ts files.
• Added a typecheck npm script and a tsconfig.json to ensure the .d.ts files are consistent with each other.
• Documentation and TypeScript definitions were updated to match those changes (obviously)

PR and Code Checklist

• semantic-release commit messages
• Run npm run reformat to have correctly formatted code

Testing

• This change adds or fixes unit tests
• Tested environment:
  • vtk.js:
  • OS:
  • Browser:

No implementation has changed; this should only affect TypeScript-aware IDEs and build tools.

[daker]

i don't know what's your use case here but they are imported like this:

import DataAccessHelper from '@kitware/vtk.js/IO/Core/DataAccessHelper';
// import '@kitware/vtk.js/IO/Core/DataAccessHelper/LiteHttpDataAccessHelper'; // Just need HTTP
import '@kitware/vtk.js/IO/Core/DataAccessHelper/HttpDataAccessHelper'; // HTTP + zip
// import '@kitware/vtk.js/IO/Core/DataAccessHelper/HtmlDataAccessHelper'; // html + base64 + zip
// import '@kitware/vtk.js/IO/Core/DataAccessHelper/JSZipDataAccessHelper'; // zip

[GalMunGral]

i don't know what's your use case here but they are imported like this:

import DataAccessHelper from '@kitware/vtk.js/IO/Core/DataAccessHelper';
// import '@kitware/vtk.js/IO/Core/DataAccessHelper/LiteHttpDataAccessHelper'; // Just need HTTP
import '@kitware/vtk.js/IO/Core/DataAccessHelper/HttpDataAccessHelper'; // HTTP + zip
// import '@kitware/vtk.js/IO/Core/DataAccessHelper/HtmlDataAccessHelper'; // html + base64 + zip
// import '@kitware/vtk.js/IO/Core/DataAccessHelper/JSZipDataAccessHelper'; // zip

I saw that HttpDataAccessHelper is imported and used here, for example:

import HttpDataAccessHelper from '@kitware/vtk.js/IO/Core/DataAccessHelper/HttpDataAccessHelper';
HttpDataAccessHelper.fetchBinary(...)

So should this be

import DataAccessHelper from '@kitware/vtk.js/IO/Core/DataAccessHelper';
import '@kitware/vtk.js/IO/Core/DataAccessHelper/HttpDataAccessHelper';
DataAccessHelper.get('http').fetchBinary(...)

instead? Or are both usages valid?

[floryst]

Thanks for adding a typecheck command!

Instead of exporting a declared const _default and changing imports to use curly braces, you can declare a value with the same name as the interface (see the following example with HtmlDataAccessHelper), and typescript will infer the type or value:

// HtmlDataAccessHelper/index.d.ts
declare const HtmlDataAccessHelper: HtmlDataAccessHelper
export default HtmlDataAccessHelper

// other.d.ts
import HtmlDataAccessHelper from '...'
// HtmlDataAccessHelper can be used as a type or a value

[floryst]

To simplify the typings, you can just do the following:

toNativeType: typeof toNativeType,
extractURLParameters: typeof extractURLParameters,

[GalMunGral]

Thanks--this is neat!

[GalMunGral]

@floryst Thanks for the suggestions! I've updated my changes.

However, removing the curly braces didn't work for me—I got errors like this from tsc:

error TS2749: 'JSZipDataAccessHelper' refers to a value, but is being used as a type here. Did you mean 'typeof JSZipDataAccessHelper'?