microsoft / microsoft/TypeScript

JSX Fragments are in-properly typed with `<></>` syntax, when using `react-jsx` JSX option

Open
#62,358 0 comments 5 reactions 1 assignee Assigned to @Copilot View on GitHub
Bug Domain: JSX/TSX Help Wanted
Dominant language
Go
Stars
111k
Forks
14.3k
PR merge metrics
PR metrics pending

Description

### 🔎 Search Terms

JSX, Fragment, children type

### 🕗 Version & Regression Information

Bug exists since TypeScript introduces `"jsx": "react-jsx"` from version 4.1.2 until `next` version (`6.0.0-dev.20250830`).

### ⏯ Playground Link

https://stackblitz.com/edit/stackblitz-starters-sffhmvvz?file=index.tsx

### 💻 Code

```tsx
import { Fragment } from "@/jsx-runtime";

{"ok"}
{({ foo }) => "also ok"}
;

<>
{"ok"}
{({ foo }) => "not ok"}
{/* ^ Binding element 'foo' implicitly has an 'any' type. */}
;
```

With following `@/jsx-runtime` definition:

```ts
export const jsx = (...args: unknown[]) => {};

type JsxElement =
| JsxElementArray
| undefined
| string
| ((arg: { foo: "bar " }) => void);
interface JsxElementArray extends Array {}

interface FragmentProps {
children?: JsxElement;
}

export const Fragment = (props: FragmentProps) => {};
```

and tsconfig:

```json
{
"compilerOptions": {
"strict": true,
"jsx": "react-jsx",
"jsxImportSource": "@",
// [...]
}
}
```

### 🙁 Actual behavior

The first JSX expression using `` pass the type checking while the second JSX using `<>` syntax reports error due to it's children was typed to `any`:
```
index.tsx:10:7 - error TS7031: Binding element 'foo' implicitly has an 'any' type.

10 {({ foo }) => "not ok"}
~~~

Found 1 error in index.tsx:10
```

### 🙂 Expected behavior

These two JSX expressions should both pass the type checking.

### Additional information about the issue

This issue was first mentioned at #50429 and fixed in #59933, but the fix only take effects on `"jsx": "react"` not `"jsx": "react-jsx"`, while the latter is a more encouraged approach in a modern project.

Contributor guide

Open the contributing guide

Assessment

This issue has not been assessed yet.

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.