Navigation Blocking

Navigation blocking is a way to prevent navigation from happening. This is typical if a user attempts to navigate while they:

Have unsaved changes
Are in the middle of a form
Are in the middle of a payment

In these situations, a prompt or custom UI should be shown to the user to confirm they want to navigate away.

If the user confirms, navigation will continue as normal
If the user cancels, all pending navigations will be blocked

Navigation blocking adds one or more layers of "blockers" to the entire underlying history API. If any blockers are present, navigation will be paused via one of the following ways:

Custom UI
- If the navigation is triggered by something we control at the router level, we can allow you to perform any task or show any UI you'd like to the user to confirm the action. Each blocker's blocker function will be asynchronously and sequentially executed. If any blocker function resolves or returns true, the navigation will be allowed and all other blockers will continue to do the same until all blockers have been allowed to proceed. If any single blocker resolves or returns false, the navigation will be canceled and the rest of the blocker functions will be ignored.
The onbeforeunload event
- For page events that we cannot control directly, we rely on the browser's onbeforeunload event. If the user attempts to close the tab or window, refresh, or "unload" the page assets in any way, the browser's generic "Are you sure you want to leave?" dialog will be shown. If the user confirms, all blockers will be bypassed and the page will unload. If the user cancels, the unload will be cancelled, and the page will remain as is.

There are 2 ways to use navigation blocking:

Hook/logical-based blocking
Component-based blocking

Hook/logical-based blocking

Let's imagine we want to prevent navigation if a form is dirty. We can do this by using the useBlocker hook:

tsx

import { useBlocker } from '@tanstack/react-router'

function MyComponent() {
  const [formIsDirty, setFormIsDirty] = useState(false)

  useBlocker({
    shouldBlockFn: () => {
      if (!formIsDirty) return false

      const shouldLeave = confirm('Are you sure you want to leave?')
      return !shouldLeave
    },
  })

  // ...
}

import { useBlocker } from '@tanstack/react-router'

function MyComponent() {
  const [formIsDirty, setFormIsDirty] = useState(false)

  useBlocker({
    shouldBlockFn: () => {
      if (!formIsDirty) return false

      const shouldLeave = confirm('Are you sure you want to leave?')
      return !shouldLeave
    },
  })

  // ...
}

shouldBlockFn gives you type safe access to the current and next location:

tsx

import { useBlocker } from '@tanstack/react-router'

function MyComponent() {
  // always block going from /foo to /bar/123?hello=world
  const { proceed, reset, status } = useBlocker({
    shouldBlockFn: ({ current, next }) => {
      return (
        current.routeId === '/foo' &&
        next.fullPath === '/bar/$id' &&
        next.params.id === 123 &&
        next.search.hello === 'world'
      )
    },
    withResolver: true,
  })

  // ...
}

import { useBlocker } from '@tanstack/react-router'

function MyComponent() {
  // always block going from /foo to /bar/123?hello=world
  const { proceed, reset, status } = useBlocker({
    shouldBlockFn: ({ current, next }) => {
      return (
        current.routeId === '/foo' &&
        next.fullPath === '/bar/$id' &&
        next.params.id === 123 &&
        next.search.hello === 'world'
      )
    },
    withResolver: true,
  })

  // ...
}

You can find more information about the useBlocker hook in the API reference.

Component-based blocking

In addition to logical/hook based blocking, can use the Block component to achieve similar results:

tsx

import { Block } from '@tanstack/react-router'

function MyComponent() {
  const [formIsDirty, setFormIsDirty] = useState(false)

  return (
    <Block
      shouldBlockFn={() => {
        if (!formIsDirty) return false

        const shouldLeave = confirm('Are you sure you want to leave?')
        return !shouldLeave
      }}
    />
  )

  // OR

  return (
    <Block shouldBlockFn={() => !formIsDirty} withResolver>
      {({ status, proceed, reset }) => <>{/* ... */}</>}
    </Block>
  )
}

import { Block } from '@tanstack/react-router'

function MyComponent() {
  const [formIsDirty, setFormIsDirty] = useState(false)

  return (
    <Block
      shouldBlockFn={() => {
        if (!formIsDirty) return false

        const shouldLeave = confirm('Are you sure you want to leave?')
        return !shouldLeave
      }}
    />
  )

  // OR

  return (
    <Block shouldBlockFn={() => !formIsDirty} withResolver>
      {({ status, proceed, reset }) => <>{/* ... */}</>}
    </Block>
  )
}

In most cases, using window.confirm in the shouldBlockFn function with withResolver: false in the hook is enough since it will clearly show the user that the navigation is being blocked and resolve the blocking based on their response.

However, in some situations, you might want to show a custom UI that is intentionally less disruptive and more integrated with your app's design.

Note: The return value of shouldBlockFn does not resolve the blocking if withResolver is true.

Hook/logical-based custom UI with resolver

tsx

import { useBlocker } from '@tanstack/react-router'

function MyComponent() {
  const [formIsDirty, setFormIsDirty] = useState(false)

  const { proceed, reset, status } = useBlocker({
    shouldBlockFn: () => formIsDirty,
    withResolver: true,
  })

  // ...

  return (
    <>
      {/* ... */}
      {status === 'blocked' && (
        <div>
          <p>Are you sure you want to leave?</p>
          <button onClick={proceed}>Yes</button>
          <button onClick={reset}>No</button>
        </div>
      )}
    </>
}

import { useBlocker } from '@tanstack/react-router'

function MyComponent() {
  const [formIsDirty, setFormIsDirty] = useState(false)

  const { proceed, reset, status } = useBlocker({
    shouldBlockFn: () => formIsDirty,
    withResolver: true,
  })

  // ...

  return (
    <>
      {/* ... */}
      {status === 'blocked' && (
        <div>
          <p>Are you sure you want to leave?</p>
          <button onClick={proceed}>Yes</button>
          <button onClick={reset}>No</button>
        </div>
      )}
    </>
}

Hook/logical-based custom UI without resolver

tsx

import { useBlocker } from '@tanstack/react-router'

function MyComponent() {
  const [formIsDirty, setFormIsDirty] = useState(false)

  useBlocker({
    shouldBlockFn: () => {
      if (!formIsDirty) {
        return false
      }

      const shouldBlock = new Promise<boolean>((resolve) => {
        // Using a modal manager of your choice
        modals.open({
          title: 'Are you sure you want to leave?',
          children: (
            <SaveBlocker
              confirm={() => {
                modals.closeAll()
                resolve(false)
              }}
              reject={() => {
                modals.closeAll()
                resolve(true)
              }}
            />
          ),
          onClose: () => resolve(true),
        })
      })
      return shouldBlock
    },
  })

  // ...
}

import { useBlocker } from '@tanstack/react-router'

function MyComponent() {
  const [formIsDirty, setFormIsDirty] = useState(false)

  useBlocker({
    shouldBlockFn: () => {
      if (!formIsDirty) {
        return false
      }

      const shouldBlock = new Promise<boolean>((resolve) => {
        // Using a modal manager of your choice
        modals.open({
          title: 'Are you sure you want to leave?',
          children: (
            <SaveBlocker
              confirm={() => {
                modals.closeAll()
                resolve(false)
              }}
              reject={() => {
                modals.closeAll()
                resolve(true)
              }}
            />
          ),
          onClose: () => resolve(true),
        })
      })
      return shouldBlock
    },
  })

  // ...
}

Component-based custom UI

Similarly to the hook, the Block component returns the same state and functions as render props:

tsx

import { Block } from '@tanstack/react-router'

function MyComponent() {
  const [formIsDirty, setFormIsDirty] = useState(false)

  return (
    <Block shouldBlockFn={() => formIsDirty} withResolver>
      {({ status, proceed, reset }) => (
        <>
          {/* ... */}
          {status === 'blocked' && (
            <div>
              <p>Are you sure you want to leave?</p>
              <button onClick={proceed}>Yes</button>
              <button onClick={reset}>No</button>
            </div>
          )}
        </>
      )}
    </Block>
  )
}

import { Block } from '@tanstack/react-router'

function MyComponent() {
  const [formIsDirty, setFormIsDirty] = useState(false)

  return (
    <Block shouldBlockFn={() => formIsDirty} withResolver>
      {({ status, proceed, reset }) => (
        <>
          {/* ... */}
          {status === 'blocked' && (
            <div>
              <p>Are you sure you want to leave?</p>
              <button onClick={proceed}>Yes</button>
              <button onClick={reset}>No</button>
            </div>
          )}
        </>
      )}
    </Block>
  )
}

How does navigation blocking work?

How do I use navigation blocking?