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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:

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​

14.0​

Migrate ImageResponse imports​

next-og-import​
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​
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​
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​
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:

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:

// '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​
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.
npx @next/codemod@latest new-link .

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

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​
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​
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:

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

Transforms into:

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​
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:

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

Transforms into:

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​
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​
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:

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.