Contributing to Next.js

Watch the 40-minute walkthrough video on how to contribute to Next.js.

Read about our Commitment to Open Source.
To contribute to our examples, please see Adding examples below.
Before jumping into a PR be sure to search existing PRs or issues for an open or closed item that relates to your submission.

Developing

The development branch is canary. This is the branch that all pull requests should be made against. The changes on the canary branch are published to the @canary tag on npm regularly.

To develop locally:

Fork this repository to your own GitHub account and then clone it to your local device.

If you don't need the whole git history, you can clone with depth 1 to reduce the download size (~1.6GB):
```
git clone --depth=1 https://github.com/vercel/next.js
```
Create a new branch:
```
git checkout -b MY_BRANCH_NAME
```
Enable pnpm:
```
corepack enable pnpm
```
Install the dependencies with:
```
pnpm install
```
Start developing and watch for code changes:
```
pnpm dev
```
In a new terminal, run pnpm types to compile declaration files from TypeScript.

Note: You may need to repeat this step if your types get outdated.

For instructions on how to build a project with your local version of the CLI, see Developing with your local version of Next.js below. (Naively linking the binary is not sufficient to develop locally.)

Building

You can build the project, including all type definitions, with:

pnpm build
# - or -
pnpm prepublishOnly

By default, the latest canary of the next-swc binaries will be installed and used. If you are actively working on Rust code or you need to test out the most recent Rust code that hasn't been published as a canary yet you can install Rust and run pnpm --filter=@next/swc build-native.

If you want to test out the wasm build locally, you will need to install wasm-pack. Run pnpm --filter=@next/swc build-wasm --target <wasm_target> to build and node ./scripts/setup-wasm.mjs to copy it into your node_modules. Run next with NODE_OPTIONS='--no-addons' to force it to use the wasm binary.

If you need to clean the project for any reason, use pnpm clean.

Testing

See the testing readme for information on writing tests.

Running tests

pnpm testonly

If you would like to run the tests in headless mode (with the browser windows hidden) you can do

pnpm testheadless

Running a specific test suite (e.g. production) inside of the test/integration directory:

pnpm testonly --testPathPattern "production"

Running one test in the production test suite:

pnpm testonly --testPathPattern "production" -t "should allow etag header support"

Linting

To check the formatting of your code:

pnpm lint

If you get errors, you can fix them with:

pnpm lint-fix

Running the example apps

Running examples can be done with:

pnpm next ./examples/basic-css/

To figure out which pages are available for the given example, you can run:

EXAMPLE=./test/integration/basic
(\
  cd $EXAMPLE/pages; \
  find . -type f \
  | grep -v '\.next' \
  | sed 's#^\.##' \
  | sed 's#index\.js##' \
  | sed 's#\.js$##' \
  | xargs -I{} echo localhost:3000{} \
)

Developing with your local version of Next.js

There are two options to develop with your local version of the codebase:

Set as a local dependency in package.json

In your app's package.json, replace:

"next": "<next-version>",

with:

"next": "file:/path/to/next.js/packages/next",

In your app's root directory, make sure to remove next from node_modules with:
```
rm -rf ./node_modules/next
```
In your app's root directory, run:
```
pnpm i
```
to re-install all of the dependencies.

Note that Next will be copied from the locally compiled version as opposed to being downloaded from the NPM registry.
Run your application as you normally would.
To update your app's dependencies, after you've made changes to your local next repository. In your app's root directory, run:
```
pnpm install --force
```

Troubleshooting

If you see the below error while running pnpm dev with next:

Failed to load SWC binary, see more info here: https://nextjs.org/docs/messages/failed-loading-swc

Try to add the below section to your package.json, then run again

"optionalDependencies": {
  "@next/swc-linux-x64-gnu": "canary",
  "@next/swc-win32-x64-msvc": "canary",
  "@next/swc-darwin-x64": "canary",
  "@next/swc-darwin-arm64": "canary"
},

Develop inside the monorepo

Move your app inside of the Next.js monorepo.
Run with pnpm next-with-deps ./app-path-in-monorepo

This will use the version of next built inside of the Next.js monorepo and the main pnpm dev monorepo command can be running to make changes to the local Next.js version at the same time (some changes might require re-running pnpm next-with-deps to take effect).

Updating documentation paths

Our documentation currently leverages a manifest file which is how documentation entries are checked.

When adding a new entry under an existing category you only need to add an entry with {title: '', path: '/docs/path/to/file.md'}. The "title" is what is shown on the sidebar.

When moving the location/url of an entry the "title" field can be removed from the existing entry and the ".md" extension removed from the "path", then a "redirect" field with the shape of {permanent: true/false, destination: '/some-url'} can be added. A new entry should be added with the "title" and "path" fields if the document was renamed within the docs folder that points to the new location in the folder e.g. /docs/some-url.md

Example of moving documentation file:

Before:

[
  {
    "path": "/docs/original.md",
    "title": "Hello world"
  }
]

After:

[
   {
      "path": "/docs/original",
      "redirect": {
         "permanent": false,
         "destination": "/new"
      }
   }
   {
      "path": "/docs/new.md",
      "title": "Hello world"
   },
]

Note: the manifest is checked automatically in the "lint" step in CI when opening a PR.

Adding warning/error descriptions

In Next.js we have a system to add helpful links to warnings and errors.

This allows for the logged message to be short while giving a broader description and instructions on how to solve the warning/error.

In general, all warnings and errors added should have these links attached.

Below are the steps to add a new link:

Run pnpm new-error which will create the error document and update the manifest automatically.
Add the following url to your warning/error: https://nextjs.org/docs/messages/<file-path-without-dotmd>.

For example, to link to errors/api-routes-static-export.md you use the url: https://nextjs.org/docs/messages/api-routes-static-export

Adding examples

When you add an example to the examples directory, please follow these guidelines to ensure high-quality examples:

TypeScript should be leveraged for new examples (no need for separate JavaScript and TypeScript examples, converting old JavaScript examples is preferred)
Examples should not add custom ESLint configuration (we have specific templates for ESLint)
If API routes aren't used in an example, they should be omitted
If an example exists for a certain library and you would like to showcase a specific feature of that library, the existing example should be updated (instead of adding a new example)
Package manager specific config should not be added (e.g. resolutions in package.json)
In package.json the version of next (and eslint-config-next) should be latest
In package.json the dependency versions should be up-to-date
Use export default function for page components and API Routes instead of const/let (The exception is if the page has getInitialProps, in which case NextPage could be useful)
CMS example directories should be prefixed with cms-
Example directories should not be prefixed with with-
Make sure linting passes (you can run pnpm lint-fix)

Also, don’t forget to add a README.md file with the following format:

Replace DIRECTORY_NAME with the directory name you’re adding.
Fill in Example Name and Description.
Examples should be TypeScript first, if possible.
Omit the name and version fields from your package.json.
Ensure all your dependencies are up to date.
Ensure you’re using next/image.
To add additional installation instructions, please add it where appropriate.
To add additional notes, add ## Notes section at the end.
Remove the Deploy your own section if your example can’t be immediately deployed to Vercel.

# Example Name

Description

## Deploy your own

Deploy the example using [Vercel](https://vercel.com?utm_source=github&utm_medium=readme&utm_campaign=next-example):

[![Deploy with Vercel](https://vercel.com/button)](https://vercel.com/new/git/external?repository-url=https://github.com/vercel/next.js/tree/canary/examples/DIRECTORY_NAME&project-name=DIRECTORY_NAME&repository-name=DIRECTORY_NAME)

## How to use

Execute [`create-next-app`](https://github.com/vercel/next.js/tree/canary/packages/create-next-app) with [npm](https://docs.npmjs.com/cli/init), [Yarn](https://yarnpkg.com/lang/en/docs/cli/create/), or [pnpm](https://pnpm.io) to bootstrap the example:

```bash
npx create-next-app --example DIRECTORY_NAME DIRECTORY_NAME-app
```

```bash
yarn create next-app --example DIRECTORY_NAME DIRECTORY_NAME-app
```

```bash
pnpm create next-app --example DIRECTORY_NAME DIRECTORY_NAME-app
```

Deploy it to the cloud with [Vercel](https://vercel.com/new?utm_source=github&utm_medium=readme&utm_campaign=next-example) ([Documentation](https://nextjs.org/docs/deployment)).

Publishing

Repository maintainers can use yarn publish-canary to publish a new version of all packages to npm.

Triaging

Repository maintainers triage every issue and PR opened in the repository.

Issues are opened with one of these labels:

template: story - a feature request, converted to an 💡 Ideas discussion
template: bug - unverified issue with Next.js itself, or one of the examples in the examples folder
template: documentation - feedback for improvement or an unverified issue with the Next.js documentation

In the case of a bug report, a maintainer looks at the provided reproduction. If the reproduction is missing or insufficient, a please add a complete reproduction label is added. If a reproduction is not provided for more than 30 days, the issue becomes stale and will be automatically closed. If a reproduction is provided within 30 days, the please add a complete reproduction label is removed and the issue will not become stale anymore.

Bug reports must be verified against the next@canary release. The canary version of Next.js ships daily and includes all features and fixes that have not been released to the stable version yet. Think of canary as a public beta. Some issues may already be fixed in the canary version, so please verify that your issue reproduces before opening a new issue. Issues not verified against next@canary will be closed after 30 days.

If the issue is specific to the project and not to Next.js itself, it might be converted to a 🎓️ Help discussion

If the bug is verified, it will receive the kind: bug label and will be tracked by the maintainers. An area: label can be added to indicate which part of Next.js is affected.

Confirmed issues never become stale or are closed before resolution.

All closed PRs and Issues will be locked after 30 days of inactivity (eg.: comment, referencing from elsewhere).

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contributing.md

contributing.md

Contributing to Next.js

Developing

Building

Testing

Running tests

Linting

Running the example apps

Developing with your local version of Next.js

Set as a local dependency in package.json

Troubleshooting

Develop inside the monorepo

Updating documentation paths

Adding warning/error descriptions

Adding examples

Publishing

Triaging

Files

contributing.md

Latest commit

History

contributing.md

File metadata and controls

Contributing to Next.js

Developing

Building

Testing

Running tests

Linting

Running the example apps

Developing with your local version of Next.js

Set as a local dependency in package.json

Troubleshooting

Develop inside the monorepo

Updating documentation paths

Adding warning/error descriptions

Adding examples

Publishing

Triaging