React Router Data Mode

Data mode uses createBrowserRouter and RouterProvider to enable data loading, actions, and pending UI without the framework's Vite plugin. This is ideal for existing React applications that want to add data loading and mutation capabilities.

When to Apply

Using createBrowserRouter with route objects
Loading data with loader property on routes
Handling mutations with action property
Navigating with <Link>, <NavLink>, <Form>, redirect, and useNavigate
Implementing pending/loading UI states with useNavigation
Using useFetcher for mutations without navigation

References

Load the relevant reference for detailed guidance on the specific API/concept:

Reference	Use When
`references/routing.md`	Configuring routes, nested routes, layout
`references/route-object.md`	Understanding route object properties
`references/data-loading.md`	Loading data with loaders
`references/actions.md`	Handling forms, mutations, validation
`references/navigation.md`	Links, programmatic navigation, redirects
`references/pending-ui.md`	Loading states, optimistic UI
`references/ssr.md`	Server-side rendering with data mode

Critical Patterns

These are the most important patterns to follow. Load the relevant reference for full details.

Basic Router Setup

import { createBrowserRouter, RouterProvider } from "react-router";

const router = createBrowserRouter([
  {
    path: "/",
    Component: Root,
    children: [
      { index: true, Component: Home },
      { path: "about", Component: About },
    ],
  },
]);

ReactDOM.createRoot(root).render(<RouterProvider router={router} />);

Forms & Mutations

Search forms - use <Form method="get">, NOT onSubmit with setSearchParams:

// ✅ Correct
<Form method="get">
  <input name="q" />
</Form>

// ❌ Wrong - don't manually handle search params
<form onSubmit={(e) => { e.preventDefault(); setSearchParams(...) }}>

Inline mutations - use useFetcher, NOT <Form> (which causes page navigation):

const fetcher = useFetcher();
const optimistic = fetcher.formData
  ? fetcher.formData.get("favorite") === "true"
  : isFavorite;

<fetcher.Form method="post" action={`/favorites/${id}`}>
  <button>{optimistic ? "★" : "☆"}</button>
</fetcher.Form>;

See references/actions.md for complete patterns.

Optimistic UI Pattern

Use fetcher.formData to show expected results immediately:

function FavoriteButton({ itemId, isFavorite }) {
  const fetcher = useFetcher();

  // Optimistic: use pending form data, fallback to server state
  const optimistic = fetcher.formData
    ? fetcher.formData.get("favorite") === "true"
    : isFavorite;

  return (
    <fetcher.Form method="post" action={`/items/${itemId}/favorite`}>
      <input type="hidden" name="favorite" value={String(!optimistic)} />
      <button>{optimistic ? "★" : "☆"}</button>
    </fetcher.Form>
  );
}

See references/pending-ui.md for complete patterns.

Further Documentation

If anything related to React Router is not covered in these references, you can search the official documentation:

https://reactrouter.com/docs

/react-router-data-mode

SKILL.md