---
title: useBlocker
---

# useBlocker

[MODES: framework, data]

## Summary

[Reference Documentation ↗](https://api.reactrouter.com/v7/functions/react_router.useBlocker.html)

Allow the application to block navigations within the SPA and present the user a confirmation dialog to confirm the navigation. Mostly used to avoid using half-filled form data. This does not handle hard-reloads or cross-origin navigations.

## Signature

```tsx
useBlocker(shouldBlock): Blocker
```

## Params

### shouldBlock

[modes: framework, data]

_No documentation_