UPGRADING.md

Migrating from v8 to v9

Breaking Changes

@zeit/next-typescript is no longer necessary

Next.js will now ignore usage @zeit/next-typescript and warn you to remove it. Please remove this plugin from your next.config.js.

Usage of fork-ts-checker-webpack-plugin should also be removed from your next.config.js.

The config key is now a special export on a page

You may no longer export a custom variable named config from a page (i.e. export { config } / export const config ...). This exported variable is now used to specify page-level Next.js configuration like Opt-in AMP and API Route features.

You must rename a non-Next.js-purposed config export to something different.

next/dynamic no longer renders "loading..." by default while loading

Dynamic components will not render anything by default while loading. You can still customize this behavior by setting the loading property:

import dynamic from 'next/dynamic'

const DynamicComponentWithCustomLoading = dynamic(
  () => import('../components/hello2'),
  {
    loading: () => <p>Loading</p>,
  }
)

withAmp has been removed in favor of an exported configuration object

Next.js now has the concept of page-level configuration, so the withAmp higher-order component has been removed for consistency.

This change can be automatically migrated by running the following commands in the root of your Next.js project:

curl -L https://github.com/zeit/next-codemod/archive/master.tar.gz | tar -xz --strip=2 next-codemod-master/transforms/withamp-to-config.js npx jscodeshift -t ./withamp-to-config.js pages/**/*.js

To perform this migration by hand, or view what the codemod will produce, see below:

Before

import { withAmp } from 'next/amp'

function Home() {
  return <h1>My AMP Page</h1>
}

export default withAmp(Home)
// or
export default withAmp(Home, { hybrid: true })

After

export default function Home() {
  return <h1>My AMP Page</h1>
}

export const config = {
  amp: true,
  // or
  amp: 'hybrid',
}

next export no longer exports pages as index.html

Previously, exporting pages/about.js would result in out/about/index.html. This behavior has been changed to result in out/about.html.

You can revert to the previous behavior by creating a next.config.js with the following content:

// next.config.js
module.exports = {
  exportTrailingSlash: true,
}

Deprecated Features

next/dynamic has deprecated loading multiple modules at once

The ability to load multiple modules at once has been deprecated in next/dynamic to be closer to React's implementation (React.lazy and Suspense).

Updating code that relies on this behavior is relatively straightforward! We've provided an example of a before/after to help you migrate your application:

Before

import dynamic from 'next/dynamic'

const HelloBundle = dynamic({
  modules: () => {
    const components = {
      Hello1: () => import('../components/hello1').then(m => m.default),
      Hello2: () => import('../components/hello2').then(m => m.default),
    }

    return components
  },
  render: (props, { Hello1, Hello2 }) => (
    <div>
      <h1>{props.title}</h1>
      <Hello1 />
      <Hello2 />
    </div>
  ),
})

function DynamicBundle() {
  return <HelloBundle title="Dynamic Bundle" />
}

export default DynamicBundle

After

import dynamic from 'next/dynamic'

const Hello1 = dynamic(() => import('../components/hello1'))
const Hello2 = dynamic(() => import('../components/hello2'))

function HelloBundle({ title }) {
  return (
    <div>
      <h1>{title}</h1>
      <Hello1 />
      <Hello2 />
    </div>
  )
}

function DynamicBundle() {
  return <HelloBundle title="Dynamic Bundle" />
}

export default DynamicBundle