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Next.js

next/router

Before moving forward, we recommend you to read Routing Introduction first.

useRouter

If you want to access the router object inside any function component in your app, you can use the useRouter hook, take a look at the following example:

import { useRouter } from 'next/router'

function ActiveLink({ children, href }) {
  const router = useRouter()
  const style = {
    marginRight: 10,
    color: router.pathname === href ? 'red' : 'black',
  }

  const handleClick = (e) => {
    e.preventDefault()
    router.push(href)
  }

  return (
    <a href={href} onClick={handleClick} style={style}>
      {children}
    </a>
  )
}

export default ActiveLink

useRouter is a React Hook, meaning it cannot be used with classes. You can either use withRouter or wrap your class in a function component.

router object

The following is the definition of the router object returned by both useRouter and withRouter:

  • pathname: String - Current route. That is the path of the page in /pages
  • query: Object - The query string parsed to an object. It will be an empty object during prerendering if the page doesn't have data fetching requirements. Defaults to {}
  • asPath: String - Actual path (including the query) shown in the browser

Additionally, the following methods are also included inside router:

router.push

Examples

Handles client-side transitions, this method is useful for cases where next/link is not enough.

router.push(url, as, options)
  • url - The URL to navigate to. This is usually the name of a page
  • as - Optional decorator for the URL that will be shown in the browser. Defaults to url
  • options - Optional object with the following configuration options:

You don't need to use router.push for external URLs. window.location is better suited for those cases.

Usage

Navigating to pages/about.js, which is a predefined route:

import { useRouter } from 'next/router'

export default function Page() {
  const router = useRouter()

  return <span onClick={() => router.push('/about')}>Click me</span>
}

Navigating pages/post/[pid].js, which is a dynamic route:

import { useRouter } from 'next/router'

export default function Page() {
  const router = useRouter()

  return (
    <span onClick={() => router.push('/post/[pid]', '/post/abc')}>
      Click me
    </span>
  )
}

Redirecting the user to pages/login.js, useful for pages behind authentication:

import { useEffect } from 'react'
import { useRouter } from 'next/router'

// Here you would fetch and return the user
const useUser = () => ({ user: null, loading: false })

export default function Page() {
  const { user, loading } = useUser()
  const router = useRouter()

  useEffect(() => {
    if (!(user || loading)) {
      router.push('/login')
    }
  }, [user, loading])

  return <p>Redirecting...</p>
}

With URL object

You can use an URL object in the same way you can use it for next/link. Works for both the url and as parameters:

import { useRouter } from 'next/router'

export default function ReadMore() {
  const router = useRouter()

  return (
    <span
      onClick={() => {
        router.push({
          pathname: '/about',
          query: { name: 'Vercel' },
        })
      }}
    >
      Click here to read more
    </span>
  )
}

router.replace

Similar to the replace prop in next/link, router.replace will prevent adding a new URL entry into the history stack.

router.replace(url, as, options)
  • The API for router.replace is exactly the same as the API for router.push.

Usage

Take a look at the following example:

import { useRouter } from 'next/router'

export default function Page() {
  const router = useRouter()

  return <span onClick={() => router.replace('/home')}>Click me</span>
}

router.prefetch

Prefetch pages for faster client-side transitions. This method is only useful for navigations without next/link, as next/link takes care of prefetching pages automatically.

This is a production only feature. Next.js doesn't prefetch pages on development.

router.prefetch(url, as)
  • url - The path to a page inside the pages directory
  • as - Optional decorator for url, used to prefetch dynamic routes. Defaults to url

Usage

Let's say you have a login page, and after a login, you redirect the user to the dashboard. For that case, we can prefetch the dashboard to make a faster transition, like in the following example:

import { useCallback, useEffect } from 'react'
import { useRouter } from 'next/router'

export default function Login() {
  const router = useRouter()
  const handleSubmit = useCallback((e) => {
    e.preventDefault()

    fetch('/api/login', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        /* Form data */
      }),
    }).then((res) => {
      // Do a fast client-side transition to the already prefetched dashboard page
      if (res.ok) router.push('/dashboard')
    })
  }, [])

  useEffect(() => {
    // Prefetch the dashboard page as the user will go there after the login
    router.prefetch('/dashboard')
  }, [])

  return (
    <form onSubmit={handleSubmit}>
      {/* Form fields */}
      <button type="submit">Login</button>
    </form>
  )
}

router.beforePopState

In some cases (for example, if using a Custom Server), you may wish to listen to popstate and do something before the router acts on it.

router.beforePopState(cb)
  • cb - The function to run on incoming popstate events. The function receives the state of the event as an object with the following props:
    • url: String - the route for the new state. This is usually the name of a page
    • as: String - the url that will be shown in the browser
    • options: Object - Additional options sent by router.push

If cb returns false, the Next.js router will not handle popstate, and you'll be responsible for handling it in that case. See Disabling file-system routing.

Usage

You could use beforePopState to manipulate the request, or force a SSR refresh, as in the following example:

import { useEffect } from 'react'
import { useRouter } from 'next/router'

export default function Page() {
  const router = useRouter()

  useEffect(() => {
    router.beforePopState(({ url, as, options }) => {
      // I only want to allow these two routes!
      if (as !== '/' && as !== '/other') {
        // Have SSR render bad routes as a 404.
        window.location.href = as
        return false
      }

      return true
    })
  }, [])

  return <p>Welcome to the page</p>
}

router.back

Navigate back in history. Equivalent to clicking the browser’s back button. It executes window.history.back().

Usage 

import { useRouter } from 'next/router'

export default function Page() {
  const router = useRouter()

  return <span onClick={() => router.back()}>Click here to go back</span>
}

router.reload

Reload the current URL. Equivalent to clicking the browser’s refresh button. It executes window.location.reload().

Usage 

import { useRouter } from 'next/router'

export default function Page() {
  const router = useRouter()

  return <span onClick={() => router.reload()}>Click here to reload</span>
}

router.events

Examples

You can listen to different events happening inside the Next.js Router. Here's a list of supported events:

  • routeChangeStart(url) - Fires when a route starts to change
  • routeChangeComplete(url) - Fires when a route changed completely
  • routeChangeError(err, url) - Fires when there's an error when changing routes, or a route load is cancelled
    • err.cancelled - Indicates if the navigation was cancelled
  • beforeHistoryChange(url) - Fires just before changing the browser's history
  • hashChangeStart(url) - Fires when the hash will change but not the page
  • hashChangeComplete(url) - Fires when the hash has changed but not the page

Here url is the URL shown in the browser. If you call router.push(url, as) (or similar), then the value of url will be as.

Note: If you configure a basePath then the value of url will be basePath + as.

Usage

For example, to listen to the router event routeChangeStart, open or create pages/_app.js and subscribe to the event, like so:

import { useEffect } from 'react'
import { useRouter } from 'next/router'

export default function MyApp({ Component, pageProps }) {
  const router = useRouter()

  useEffect(() => {
    const handleRouteChange = (url) => {
      console.log('App is changing to: ', url)
    }

    router.events.on('routeChangeStart', handleRouteChange)

    // If the component is unmounted, unsubscribe
    // from the event with the `off` method:
    return () => {
      router.events.off('routeChangeStart', handleRouteChange)
    }
  }, [])

  return <Component {...pageProps} />
}

We use a Custom App (pages/_app.js) for this example to subscribe to the event because it's not unmounted on page navigations, but you can subscribe to router events on any component in your application.

Router events should be registered when a component mounts (useEffect or componentDidMount / componentWillUnmount) or imperatively when an event happens.

If a route load is cancelled (for example, by clicking two links rapidly in succession), routeChangeError will fire. And the passed err will contain a cancelled property set to true, as in the following example:

import { useEffect } from 'react'
import { useRouter } from 'next/router'

export default function MyApp({ Component, pageProps }) {
  const router = useRouter()

  useEffect(() => {
    const handleRouteChangeError = (err, url) => {
      if (err.cancelled) {
        console.log(`Route to ${url} was cancelled!`)
      }
    }

    router.events.on('routeChangeError', handleRouteChangeError)

    // If the component is unmounted, unsubscribe
    // from the event with the `off` method:
    return () => {
      router.events.off('routeChangeError', handleRouteChangeError)
    }
  }, [])

  return <Component {...pageProps} />
}

withRouter

If useRouter is not the best fit for you, withRouter can also add the same router object to any component.

Usage 

import { withRouter } from 'next/router'

function Page({ router }) {
  return <p>{router.pathname}</p>
}

export default withRouter(Page)
CLInext/link