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TanStack Router + React Guidelines

Core Philosophy

• TanStack Router is 100% type-safe — leverage TypeScript generics for route params, search params, and loader data
• Prefer file-based routing for scalability; use code-based routing only for highly dynamic use cases
• Always define routes with createFileRoute or createRootRoute — never use plain objects
• Route data loading belongs in loader functions, not in component useEffect
• Search params are first-class citizens — define their schema with Zod or Valibot for validation and type inference

Project Setup

• Use @tanstack/react-router with Vite and the @tanstack/router-vite-plugin for file-based routing
• Enable routeTree.gen.ts auto-generation — never manually edit this file
• Structure routes under src/routes/ directory
• Root layout goes in src/routes/__root.tsx
• Use src/routes/index.tsx for the home/index route

File-Based Route Conventions

src/routes/
  __root.tsx          ← Root layout (wraps all routes)
  index.tsx           ← / route
  about.tsx           ← /about route
  posts/
    index.tsx         ← /posts route
    $postId.tsx       ← /posts/:postId (dynamic segment)
    _layout.tsx       ← Layout route (no path segment)
  _auth/
    login.tsx         ← /login (grouped under auth layout)
  (admin)/
    dashboard.tsx     ← /dashboard (pathless group)

Route Definition Patterns

// src/routes/posts/$postId.tsx
import { createFileRoute } from '@tanstack/react-router'

export const Route = createFileRoute('/posts/$postId')({
  loader: async ({ params }) => {
    return fetchPost(params.postId) // fully typed params
  },
  component: PostComponent,
})

function PostComponent() {
  const post = Route.useLoaderData() // type-safe loader data
  const { postId } = Route.useParams() // type-safe params
  return <div>{post.title}</div>
}

Type-Safe Search Params

• Always define search param schemas using z.object() from Zod
• Use validateSearch option on route definition
• Access with Route.useSearch() — never read raw window.location.search

import { z } from 'zod'
import { createFileRoute } from '@tanstack/react-router'

const searchSchema = z.object({
  page: z.number().int().min(1).default(1),
  q: z.string().optional(),
})

export const Route = createFileRoute('/search')({
  validateSearch: searchSchema,
  component: SearchPage,
})

function SearchPage() {
  const { page, q } = Route.useSearch()
  // ...
}

Navigation

• Use <Link> from @tanstack/react-router — never <a href> for internal navigation
• Use useNavigate() for programmatic navigation
• Always pass typed params and search to Link — the compiler will catch mistakes

import { Link, useNavigate } from '@tanstack/react-router'

// Declarative
<Link to="/posts/$postId" params={{ postId: '123' }}>View Post</Link>

// Programmatic
const navigate = useNavigate()
navigate({ to: '/posts/$postId', params: { postId: post.id } })

Loaders & Data Fetching

• Use loader for data that must be available before render (no loading spinners for critical data)
• Integrate with TanStack Query by using ensureQueryData inside loaders for caching
• Use staleTime on loaders to avoid redundant fetches during navigation
• Return plain serializable data from loaders — no class instances

export const Route = createFileRoute('/posts')({
  loader: ({ context: { queryClient } }) =>
    queryClient.ensureQueryData(postsQueryOptions()),
  component: PostsPage,
})

Error Handling

• Define errorComponent on routes to handle loader or render errors
• Use notFoundComponent for 404 states within a route subtree
• Use pendingComponent for showing skeletons/spinners during data loading

export const Route = createFileRoute('/posts/$postId')({
  loader: fetchPost,
  errorComponent: ({ error }) => <ErrorBanner message={error.message} />,
  pendingComponent: () => <PostSkeleton />,
  notFoundComponent: () => <NotFound />,
  component: PostDetail,
})

Router Context

• Use router context to inject global dependencies (queryClient, auth, theme) into loaders
• Define context type in __root.tsx and pass it when creating the router

// __root.tsx
import { createRootRouteWithContext } from '@tanstack/react-router'

interface RouterContext {
  queryClient: QueryClient
  auth: AuthState
}

export const Route = createRootRouteWithContext<RouterContext>()({
  component: RootLayout,
})

// main.tsx
const router = createRouter({
  routeTree,
  context: { queryClient, auth },
})

Route Guards / Auth

• Use beforeLoad for authentication checks — redirect to login if unauthenticated
• Never put auth logic inside components — handle it at the routing layer

export const Route = createFileRoute('/_auth/dashboard')({
  beforeLoad: ({ context }) => {
    if (!context.auth.isAuthenticated) {
      throw redirect({ to: '/login' })
    }
  },
  component: Dashboard,
})

Performance

• Use preload on <Link> to trigger loader prefetching on hover/focus
• Set defaultPreload: 'intent' on the router for automatic preloading
• Use gcTime and staleTime on loaders to tune cache behavior
• Lazy-load route components with React.lazy for code splitting

DevTools

• Install @tanstack/router-devtools and render <TanStackRouterDevtools /> in development
• Use devtools to inspect route tree, active matches, loader data, and search params

Testing

• Use createMemoryHistory and createRouter to create isolated router instances in tests
• Wrap components under test with <RouterProvider router={testRouter} />
• Mock loaders by providing fake context values