f73e7d51ad
I would like to be able to write handlers with early returns like this:
```typescript
import { NextApiHandler } from 'next'
const handler: NextApiHandler = (req, res) => {
const value = getStuff()
if (value === 'branch') {
return res.json({})
}
res.status(400)
}
```
but `NextApiHandler`'s current return type is `void | Promise<void>`, which causes compilation to fail with
```
Error:(11, 3) TS2322: Type '(req: NextApiRequest, res: NextApiResponse<any>) => Promise<NextApiResponse<any> | undefined>' is not assignable to type 'NextApiHandler<any>'.
Type 'Promise<NextApiResponse<any> | undefined>' is not assignable to type 'void | Promise<void>'.
Type 'Promise<NextApiResponse<any> | undefined>' is not assignable to type 'Promise<void>'.
Type 'NextApiResponse<any> | undefined' is not assignable to type 'void'.
Type 'NextApiResponse<any>' is not assignable to type 'void'.
```
to avoid that the above snippet needs to be written as
```typescript
if (value === 'branch') {
res.json({})
return
}
```
which looks odd to me. Changing the return type of `NextApiHandler` to `unknown | Promise<unknown>` would allow for shorter early returns and still communicates to users that nothing is expected to be returned from a handler.
Augmenting the type like this, makes the first snippet work:
```typescript
import { NextApiRequest, NextApiResponse } from 'next'
declare module 'next' {
export declare type NextApiHandler<T = any> = (
req: NextApiRequest,
res: NextApiResponse<T>
) => unknown | Promise<unknown>
}
```
## Bug
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`
## Feature
- [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have helpful link attached, see `contributing.md`
## Documentation / Examples
- [ ] Make sure the linting passes by running `yarn lint`
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|---|---|---|
| .. | ||
| create-next-app | ||
| eslint-config-next | ||
| eslint-plugin-next | ||
| next | ||
| next-bundle-analyzer | ||
| next-codemod | ||
| next-env | ||
| next-mdx | ||
| next-plugin-storybook | ||
| next-polyfill-module | ||
| next-polyfill-nomodule | ||
| next-swc | ||
| react-dev-overlay | ||
| react-refresh-utils | ||