React SPA Patterns

This skill covers @clerk/react for Vite/CRA SPAs. For Next.js use clerk-nextjs-patterns. For TanStack Start use clerk-tanstack-patterns.

What Do You Need?

Task

Reference

useAuth / useUser / useClerk hooks

references/hooks.md

Protected routes with React Router

references/protected-routes.md

Custom sign-in / sign-up forms

references/custom-flows.md

React Router v6/v7 integration

references/router-integration.md

References

Reference

Description

references/hooks.md

useAuth, isLoaded guard

references/protected-routes.md

ProtectedRoute pattern

references/custom-flows.md

useSignIn, useSignUp flows

references/router-integration.md

React Router v6/v7 setup

Setup

npm install @clerk/react

.env:

VITE_CLERK_PUBLISHABLE_KEY=pk_...

src/main.tsx:

import { StrictMode } from 'react'

import { createRoot } from 'react-dom/client'

import { ClerkProvider } from '@clerk/react'

import App from './App.tsx'

const PUBLISHABLE_KEY = import.meta.env.VITE_CLERK_PUBLISHABLE_KEY

createRoot(document.getElementById('root')!).render(

  <StrictMode>

    <ClerkProvider publishableKey={PUBLISHABLE_KEY}>

      <App />

    </ClerkProvider>

  </StrictMode>,

)

Mental Model

@clerk/react is client-only — there is no server-side auth(). All auth state comes from hooks.

• isLoaded must be true before trusting isSignedIn — always guard on isLoaded

• useClerk() gives access to signOut, openSignIn, openUserProfile and other methods

• getToken() from useAuth() fetches the session JWT for API calls

Minimal Pattern

import { useAuth } from '@clerk/react'

export function Dashboard() {

  const { isLoaded, isSignedIn, userId } = useAuth()

  if (!isLoaded) return <div>Loading...</div>

  if (!isSignedIn) return <div>Please sign in</div>

  return <div>Hello {userId}</div>

}

Protected Route (React Router v6/v7)

import { Navigate, Outlet } from 'react-router-dom'

import { useAuth } from '@clerk/react'

export function ProtectedRoute() {

  const { isLoaded, isSignedIn } = useAuth()

  if (!isLoaded) return <div>Loading...</div>

  if (!isSignedIn) return <Navigate to="/sign-in" replace />

  return <Outlet />

}

<Routes>

  <Route element={<ProtectedRoute />}>

    <Route path="/dashboard" element={<Dashboard />} />

    <Route path="/settings" element={<Settings />} />

  </Route>

  <Route path="/sign-in" element={<SignIn />} />

</Routes>

Token for API Calls

import { useAuth } from '@clerk/react'

export function DataFetcher() {

  const { getToken } = useAuth()

  async function fetchData() {

    const token = await getToken()

    if (!token) return

    const res = await fetch('/api/data', {

      headers: { Authorization: `Bearer ${token}` },

    })

    return res.json()

  }

  return <button onClick={fetchData}>Load</button>

}

Common Pitfalls

Symptom

Cause

Fix

isSignedIn is undefined

isLoaded is still false

Always check isLoaded first

ClerkProvider missing

Provider not at root

Wrap <App> in main.tsx

Env var undefined

Wrong Vite prefix

Use VITE_CLERK_PUBLISHABLE_KEY, access via import.meta.env

Token is null

User not signed in

Null-check getToken() result

Sign-in component shows blank

No publishableKey on provider

Pass publishableKey explicitly

See Also

• clerk-setup - Initial Clerk install

• clerk-custom-ui - Custom flows & appearance

• clerk-orgs - B2B organizations

Docs

React SDK