ESM types are described incorrectly

[dsherret]

https://arethetypeswrong.github.io/?p=preact-render-to-string%406.6.5

I started working on this a bit, but the repo needs a bit of a larger overhaul that would be better for a maintainer to do.

// package.json
{
  "dependencies": {
    "preact": "^10.28.2",
    "preact-render-to-string": "^6.6.5",
    "typescript": "^5.9.3"
  }
}

// tsconfig.json
{
  "compilerOptions": {
    "module": "nodenext",
    "target": "esnext",
    "types": [],
    "noEmit": true,
    "noUncheckedIndexedAccess": true,
    "exactOptionalPropertyTypes": true,
    "strict": true,
    "jsx": "react-jsx",
    "verbatimModuleSyntax": true,
    "isolatedModules": true,
    "noUncheckedSideEffectImports": true,
    "moduleDetection": "force",
    "skipLibCheck": true,
  }
}

// main.mts
import renderToString, { shallowRender, render } from "preact-render-to-string/jsx";
import { h } from "preact";

console.log(shallowRender);
console.log(render);
console.log(renderToString(h("div", {})))

> npx tsc --noEmit
main.mts:6:13 - error TS2349: This expression is not callable.
  Type 'typeof import("V:/scratch/node_modules/preact-render-to-string/dist/jsx")' has no call signatures.

6 console.log(renderToString(h("div", {})))
              ~~~~~~~~~~~~~~


Found 1 error in main.mts:6

[rschristian]

w/ node16 resolution, this repo matches what we do elsewhere: https://arethetypeswrong.github.io/?p=preact%4010.28.2, https://arethetypeswrong.github.io/?p=%40preact%2Fsignals%402.5.1

We're generally not entertaining the .d.cts & .d.mts thing.

[dsherret]

Not sure what you mean. Are you saying this one shouldn't be fixed? I think using .d.mts for newer Node might be a way to fix it (the repo is using .mjs in the build output) and then properly use export = to describe the CJS files instead of export default.

In this case, it doesn't work from Node ESM because it resolves to the ./jsx.d.ts file, which typescript thinks is describing a CJS file instead of ESM. Then the default export falls apart.

The way to work around this is to do:

// main.mts
import renderToStringDefault from "preact-render-to-string/jsx";
const renderToString = (renderToStringDefault) as unknown as (typeof import("preact-render-to-string/jsx"))["default"];

[rschristian]

IIUC and you're referring to the "Masquerading as CJS", I'm saying it's very unlikely at this point that any maintainer is going to address it. Our tooling across our repos does not support doing this automatically and (mostly) duplicating type declaration files manually is sorta miserable.

This has existed for years now and I think we've mostly made our peace with it, for better or for worse.

[dsherret]

One way to easily somewhat resolve it would be to provide a named export in addition to the default export for the ./jsx path then tell people to just use the named export (the slowly work towards #185).