better support .js as entry point, and need more verbose info on slow types

[hrgdavor]

I am trying to publish a tiny utility to test jsr. I really do not want to write typescript, I am ok with providing good typescript support.

why is jsr having issue with this index.js

/**
 * Map string values returned by {URLSearchParams} to boolean.
 * /?param - empty string -> true
 * /?param=1 - "1" -> true
 * /?param=true - "true" -> true
 *
 * false otherwise
 *
 * @param {string|null} val
 * @returns {boolean} boolean
 */
export const urlBool = val => {
  if (val === '' || val === '1' || val === 'true') return true
  return false
}

npx jsr publish --dry-run gives this warning

warning[unsupported-javascript-entrypoint]: used a JavaScript module without type declarations as an entrypoint
 --> C:\wrk\jsx6\libs\url-util\index.js
  = hint: add a type declaration (d.ts) for the JavaScript module, or rewrite it to TypeScript

  info: JavaScript files with no corresponding declaration require type inference to be type checked
  info: fast check avoids type inference, so JavaScript entrypoints should be avoided

I am open to suggestions how to improve the above, if it is possible without too much hassle. jsr.io is a nice idea, but for me ATM is too agressive.

[marvinhagemeister]

Related #494

[hrgdavor]

@marvinhagemeister thanks for the reference. I will be watching that issue, and try jsr.io again once #494 is resolved.

[crowlKats]

Closing in favour of #494 since it encompasses this