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Codemods

Codemods are transformations that run on your codebase programmatically. This allows a large number of changes to be programmatically applied without having to manually go through every file.

Next.js provides Codemod transformations to help upgrade your Next.js codebase when an API is updated or deprecated.

Usage

In your terminal, navigate (cd) into your project's folder, then run:

Terminal

npx @next/codemod <transform> <path>

Replacing <transform> and <path> with appropriate values.

transform - name of transform
path - files or directory to transform
--dry Do a dry-run, no code will be edited
--print Prints the changed output for comparison

Next.js Codemods

15.0

Migrate to async Dynamic APIs

APIs that opted into dynamic rendering that previously supported synchronous access are now asynchronous. You can read more about this breaking change in the upgrade guide.

`next-async-request-api`

Terminal

npx @next/codemod@latest next-async-request-api .

This codemod will transform dynamic APIs (cookies(), headers() and draftMode() from next/headers) that are now asynchronous to be properly awaited or wrapped with React.use() if applicable. When an automatic migration isn't possible, the codemod will either add a typecast (if a TypeScript file) or a comment to inform the user that it needs to be manually reviewed & updated.

For example:

import { cookies, headers } from 'next/headers'
const token = cookies().get('token')
 
function useToken() {
  const token = cookies().get('token')
  return token
}
 
export default function Page() {
  const name = cookies().get('name')
}
 
function getHeader() {
  return headers().get('x-foo')
}

Transforms into:

import { use } from 'react'
import { cookies, headers, type UnsafeUnwrappedCookies } from 'next/headers'
 
const token = (await cookies()).get('token')
 
function useToken() {
  const token = use(cookies()).get('token')
  return token
}
 
export default function Page() {
  const name = (await cookies()).get('name')
}
 
function getHeader() {
  return (headers() as UnsafeUnwrappedCookies).get('x-foo')
}

When we detect property access on the params or searchParams props in the page / route entries (page.js, layout.js, route.js, or default.js) or the generateMetadata / generateViewport APIs, it will attempt to transform the callsite from a sync to an async function, and await the property access. If it can't be made async (such as with a client component), it will use React.use to unwrap the promise .

For example:

// page.tsx
export default function Page({
  params,
  searchParams,
}: {
  params: { slug: string }
  searchParams: { [key: string]: string | string[] | undefined }
}) {
  const { value } = searchParams
  if (value === 'foo') {
    // ...
  }
}
 
export function generateMetadata({ params }: { params: { slug: string } }) {
  return {
    title: `My Page - ${slug}`,
  }
}

Transforms into:

// page.tsx
export default function Page(props: {
  params: { slug: string }
  searchParams: { [key: string]: string | string[] | undefined }
}) {
  const { value } = await props.searchParams
  if (value === 'foo') {
    // ...
  }
}
 
export function generateMetadata(props: { params: { slug: string } }) {
  const { slug } = await props.params
  return {
    title: `My Page - ${slug}`,
  }
}

Good to know: When this codemod identifies a spot that might require manual intervention, but we aren't able to determine the exact fix, it will add a comment or typecast to the code to inform the user that it needs to be manually updated. These comments are prefixed with Next.js Dynamic Async API Codemod, and typecasts are prefixed with UnsafeUnwrapped. Your build will error until these comments are explicitly removed.

Replace `geo` and `ip` properties of `NextRequest` with `@vercel/functions`

`next-request-geo-ip`

Terminal

npx @next/codemod@latest next-request-geo-ip .

This codemod installs @vercel/functions and transforms geo and ip properties of NextRequest with corresponding @vercel/functions features.

For example:

import type { NextRequest } from 'next/server'
 
export function GET(req: NextRequest) {
  const { geo, ip } = req
}

Transforms into:

import type { NextRequest } from 'next/server'
import { geolocation, ipAddress } from '@vercel/functions'
 
export function GET(req: NextRequest) {
  const geo = geolocation(req)
  const ip = ipAddress(req)
}

Transform `next/dynamic` imports accessing named exports to return an object with a `default` property

`next-dynamic-access-named-export`

Terminal

npx @next/codemod@latest next-dynamic-access-named-export .

This codemod transforms dynamic imports using next/dynamic to ensure they return an object with a default property when accessing named exports. This aligns the behavior with React.lazy and addresses issues with accessing named exports from client components in server components.

For example:

import dynamic from 'next/dynamic'
 
const ComponentA = dynamic(() =>
  import('../components/a').then((mod) => mod.default)
)
 
const ComponentB = dynamic(() =>
  import('../components/b').then((mod) => mod.ComponentB)
)

Transforms into:

import dynamic from 'next/dynamic'
 
const ComponentA = dynamic(() =>
  import('../components/a').then((mod) => ({ default: mod.default }))
)
 
const ComponentB = dynamic(() =>
  import('../components/b').then((mod) => ({ default: mod.ComponentB }))
)

Good to know: This codemod only affects dynamic imports using next/dynamic and access named exports.

14.0

Migrate `ImageResponse` imports

`next-og-import`

Terminal

npx @next/codemod@latest next-og-import .

This codemod moves transforms imports from next/server to next/og for usage of Dynamic OG Image Generation.

For example:

import { ImageResponse } from 'next/server'

Transforms into:

import { ImageResponse } from 'next/og'

Use `viewport` export

`metadata-to-viewport-export`

Terminal

npx @next/codemod@latest metadata-to-viewport-export .

This codemod migrates certain viewport metadata to viewport export.

For example:

export const metadata = {
  title: 'My App',
  themeColor: 'dark',
  viewport: {
    width: 1,
  },
}

Transforms into:

export const metadata = {
  title: 'My App',
}
 
export const viewport = {
  width: 1,
  themeColor: 'dark',
}

13.2

Use Built-in Font

`built-in-next-font`

Terminal

npx @next/codemod@latest built-in-next-font .

This codemod uninstalls the @next/font package and transforms @next/font imports into the built-in next/font.

For example:

import { Inter } from '@next/font/google'

Transforms into:

import { Inter } from 'next/font/google'

13.1.2

Transform App Router Route Segment Config `runtime` value from `experimental-edge` to `edge`

`app-dir-runtime-config-experimental-edge`

Note: This codemod is App Router specific.

Terminal

npx @next/codemod@latest app-dir-runtime-config-experimental-edge .

This codemod transforms Route Segment Config runtime value experimental-edge to edge.

For example:

export const runtime = 'experimental-edge'

Transforms into:

export const runtime = 'edge'

13.0

Rename Next Image Imports

`next-image-to-legacy-image`

Terminal

npx @next/codemod@latest next-image-to-legacy-image .

Safely renames next/image imports in existing Next.js 10, 11, or 12 applications to next/legacy/image in Next.js 13. Also renames next/future/image to next/image.

For example:

pages/index.js

import Image1 from 'next/image'
import Image2 from 'next/future/image'
 
export default function Home() {
  return (
    <div>
      <Image1 src="/test.jpg" width="200" height="300" />
      <Image2 src="/test.png" width="500" height="400" />
    </div>
  )
}

Transforms into:

pages/index.js

// 'next/image' becomes 'next/legacy/image'
import Image1 from 'next/legacy/image'
// 'next/future/image' becomes 'next/image'
import Image2 from 'next/image'
 
export default function Home() {
  return (
    <div>
      <Image1 src="/test.jpg" width="200" height="300" />
      <Image2 src="/test.png" width="500" height="400" />
    </div>
  )
}

Migrate to the New Image Component

`next-image-experimental`

Terminal

npx @next/codemod@latest next-image-experimental .

Dangerously migrates from next/legacy/image to the new next/image by adding inline styles and removing unused props.

Removes layout prop and adds style.
Removes objectFit prop and adds style.
Removes objectPosition prop and adds style.
Removes lazyBoundary prop.
Removes lazyRoot prop.

Remove `<a>` Tags From Link Components

`new-link`

Terminal

npx @next/codemod@latest new-link .

Remove <a> tags inside Link Components, or add a legacyBehavior prop to Links that cannot be auto-fixed.

For example:

<Link href="/about">
  <a>About</a>
</Link>
// transforms into
<Link href="/about">
  About
</Link>
 
<Link href="/about">
  <a onClick={() => console.log('clicked')}>About</a>
</Link>
// transforms into
<Link href="/about" onClick={() => console.log('clicked')}>
  About
</Link>

In cases where auto-fixing can't be applied, the legacyBehavior prop is added. This allows your app to keep functioning using the old behavior for that particular link.

const Component = () => <a>About</a>
 
<Link href="/about">
  <Component />
</Link>
// becomes
<Link href="/about" legacyBehavior>
  <Component />
</Link>

11

Migrate from CRA

`cra-to-next`

Terminal

npx @next/codemod cra-to-next

Migrates a Create React App project to Next.js; creating a Pages Router and necessary config to match behavior. Client-side only rendering is leveraged initially to prevent breaking compatibility due to window usage during SSR and can be enabled seamlessly to allow the gradual adoption of Next.js specific features.

Please share any feedback related to this transform in this discussion.

10

Add React imports

`add-missing-react-import`

Terminal

npx @next/codemod add-missing-react-import

Transforms files that do not import React to include the import in order for the new React JSX transform to work.

For example:

my-component.js

export default class Home extends React.Component {
  render() {
    return <div>Hello World</div>
  }
}

Transforms into:

my-component.js

import React from 'react'
export default class Home extends React.Component {
  render() {
    return <div>Hello World</div>
  }
}

npx @next/codemod name-default-component

Versions 9 and above.

Transforms anonymous components into named components to make sure they work with Fast Refresh.

For example:

my-component.js

export default function () {
  return <div>Hello World</div>
}

Transforms into:

my-component.js

export default function MyComponent() {
  return <div>Hello World</div>
}

The component will have a camel-cased name based on the name of the file, and it also works with arrow functions.

npx @next/codemod withamp-to-config

Transforms the withAmp HOC into Next.js 9 page configuration.

For example:

// Before
import { withAmp } from 'next/amp'
 
function Home() {
  return <h1>My AMP Page</h1>
}
 
export default withAmp(Home)

// After
export default function Home() {
  return <h1>My AMP Page</h1>
}
 
export const config = {
  amp: true,
}

npx @next/codemod url-to-withrouter

Transforms the deprecated automatically injected url property on top level pages to using withRouter and the router property it injects. Read more here: https://nextjs.org/docs/messages/url-deprecated

For example:

From

import React from 'react'
export default class extends React.Component {
  render() {
    const { pathname } = this.props.url
    return <div>Current pathname: {pathname}</div>
  }
}

import React from 'react'
import { withRouter } from 'next/router'
export default withRouter(
  class extends React.Component {
    render() {
      const { pathname } = this.props.router
      return <div>Current pathname: {pathname}</div>
    }
  }
)

This is one case. All the cases that are transformed (and tested) can be found in the __testfixtures__ directory.