Exported optional null types have incorrect typescript type in the downloaded NPM package

[jchen42703]

Problem Description

For example, for the SveltyPicker:

When optional null types are exported using JSDoc like:

SveltyPicker.svelte

  /** @type {string|string[]|null} */
  export let value = null;
  /** @type {Date|Date[]|null} */
  export let initialDate = null;

The resulting typescript types are:

SveltyPicker.svelte.d.ts

 value?: string | string[];
 initialDate?: Date | Date[];

These are not the same types at all! The JS type assumes that the type is optional and defaults to null BUT the typescript example assumes the values default to undefined.

This has been the cause of a copy nasty validation bugs on our end because the type checker incorrectly tells you to change your default value to undefined, which causes our optional checks to fail.

Solution

No clue why the type exporter does this tbh...

[mskocik]

Check the latest (v5.2.11) version with corrected types