Parcel 2: Typescript + Preact

🐛 bug report

Parcel remove unused Preact h in typescript (works with js):

Uncaught ReferenceError: h is not defined

💁 Possible Solution

looks like wrong jsxFactory detection, even if I add tsconfig.json with:

  "compilerOptions": {
    "jsx": "react",
    "jsxFactory": "h"
  },

I tried to investigate:

• transformer-typescript-tsc doesn’t run by default, right?
• but transformer-babel has jsx pragma logic should this work with the Typescript?

💻 Code Sample

// unused `h`
import { h, render } from "preact";

const App = () => <div>Hello world!</div>;

// works if uncomment:
// console.log(h);

const node = document.getElementById("root");

render(<App />, node!, node!.lastChild as Element);

🌍 Your Environment

Software	Version(s)
Parcel	2.0.0-alpha.1.1
Node	v10.14.1
npm	6.10.3
Operating System	macOS
preact	10.0.0-rc.1

[mischnic]

@zackkrida I’m sorry, this is correct (babel’s typescript preset doesn’t react the tsconfig file):

{
	"presets": [["@babel/preset-typescript", {"jsxPragma": "h"}]]
}

[zackkrida]

@mischnic The recommended configuration above does not work. I made a minimal a repro as possible here: https://github.com/zackkrida/play/tree/parcel2/ts-preact-issue

I have both the specified .babelrc

{
  "presets": ["@babel/preset-typescript"],
  "plugins": [["@babel/plugin-transform-react-jsx", { "pragma": "h" }]]
}

and tsconfig.json

{
  "compilerOptions": {
    "jsxFactory": "h",
    "jsx": "react"
  }
}

and still have the ReferenceError: h is not defined error. The “unused”, imported ‘h’ in my index.tsx file is still stripped out.