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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

Codemods

15.0

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'

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,
  type UnsafeUnwrappedHeaders,
} from 'next/headers'
const token = (cookies() as unknown as UnsafeUnwrappedCookies).get('token')
 
function useToken() {
  const token = use(cookies()).get('token')
  return token
}
 
export default async function Page() {
  const name = (await cookies()).get('name')
}
 
function getHeader() {
  return (headers() as unknown as UnsafeUnwrappedHeaders).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 } }) {
  const { slug } = params
  return {
    title: `My Page - ${slug}`,
  }
}

Transforms into:

// page.tsx
export default async function Page(props: {
  params: Promise<{ slug: string }>
  searchParams: Promise<{ [key: string]: string | string[] | undefined }>
}) {
  const searchParams = await props.searchParams
  const { value } = searchParams
  if (value === 'foo') {
    // ...
  }
}
 
export async function generateMetadata(props: {
  params: Promise<{ slug: string }>
}) {
  const params = await props.params
  const { slug } = 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/codemod, and typecasts are prefixed with UnsafeUnwrapped. Your build will error until these comments are explicitly removed. Read more.

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)
}

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'

13.0

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.
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>
  }
}

9

Transform Anonymous Components into Named Components

name-default-component
Terminal
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.

8

Transform AMP HOC into page config

withamp-to-config
Terminal
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,
}

6

Use withRouter

url-to-withrouter
Terminal
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>
  }
}
To
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.