Hello! I was using `npx create-next-app --ts` to quickly bootstrap a basic next.js project with Typescript. It bothered me that I got git diff just from running `npm run build` inside the project, because the new notice in the `next-env.d.ts` file.
So I went ahead and updated the `next-env.d.ts` file in [`packages/create-next-app/templates/typescript`](fb67ce9864/packages/create-next-app/templates/typescript/next-env.d.ts) to be exactly how the file looks after running once. (7417ecc09c)
Then I realized that I could probably do the same for all the `next-env.d.ts` that are spread out in the many examples, to make running those examples after cloning them feel a bit smoother. (fb67ce9864)
> However I skipped the [`with-typescript-graphql`](40f85f6d95/examples/with-typescript-graphql) example since that [`next-env.d.ts`](40f85f6d95/examples/with-typescript-graphql/next-env.d.ts (L4-L9)) actually has changes and I couldn't even run `yarn build` in that example, so I'm not sure what will happen with the `next-env.d.ts`. Someone who _gets_ that example will have to fix it I suppose.
This adds a type annotation for the `NextConfig` type to `next.config.js` in the `create-next-app` typescript template.
## 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
This PR introduces an improved developer experience when `next lint` is run for the first time.
### Current behavior
`eslint-config-next` is a required package that must be installed before proceeding with `next lint` or `next build`:
Although this has helped many developers start using the new ESLint config, this has also resulted in a few issues:
- Users are required to install the full config (`eslint-config-next`) even if they do not use it or use the Next.js plugin directly (`eslint-plugin-next`).
- #26348
- There's some confusion on why `eslint-config-next` needs to be installed or how it should be used instead of `eslint-plugin-next`.
- #26574
- #26475
- #26438
### New behavior
Instead of enforcing `eslint-config-next` as a required package, this PR prompts the user by asking what config they would like to start. This happens when `next lint` is run for the first time **and** if no ESLint configuration is detected in the application.
<img src="https://user-images.githubusercontent.com/12476932/124331177-e1668a80-db5c-11eb-8915-38d3dc20f5d4.gif" width="800" />
- The CLI will take care of installing `eslint` or `eslint-config-next` if either is not already installed
- Users now have the option to choose between a strict configuration (`next/core-web-vitals`) or just the base configuration (`next`)
- For users that decide to create their own ESLint configuration, or already have an existing one, **installing `eslint-config-next` will not be a requirement for `next lint` or `next build` to run**. A warning message will just show if the Next.js ESLint plugin is not detected in an ESLint config.
<img width="682" alt="Screen Shot 2021-06-25 at 3 02 12 PM" src="https://user-images.githubusercontent.com/12476932/123473329-6cc4a680-d5c6-11eb-9a57-d5c0b89a2732.png">
---
In addition, this PR also:
- Fixes#26348
- Updates documentation to make it more clear what approach to take for new and existing ESLint configurations
## Documentation / Examples
- [x] Make sure the linting passes
### Changes
* Corrected the file extension reference from .tsx to .ts for ```packages/create-next-app/templates/typescript/README-template.md```.
This matches the actual file extension and avoids confusion for new users.
