createBrowserRouter

This is the recommended router for all React Router web projects. It uses the DOM History API to update the URL and manage the history stack.

It also enables the v6.4 data APIs like loaders, actions, fetchers and more.

Due to the decoupling of fetching and rendering in the design of the data APIs, you should create your router outside of the React tree with a statically defined set of routes. For more information on this design, please see the Remixing React Router blog post and the When to Fetch conference talk.

import * as React from "react";
import * as ReactDOM from "react-dom";
import {
  createBrowserRouter,
  RouterProvider,
} from "react-router-dom";

import Root, { rootLoader } from "./routes/root";
import Team, { teamLoader } from "./routes/team";

const router = createBrowserRouter([
  {
    path: "/",
    element: <Root />,
    loader: rootLoader,
    children: [
      {
        path: "team",
        element: <Team />,
        loader: teamLoader,
      },
    ],
  },
]);

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

Type Declaration

function createBrowserRouter(
  routes: RouteObject[],
  opts?: {
    basename?: string;
    future?: FutureConfig;
    hydrationData?: HydrationState;
    unstable_dataStrategy?: unstable_DataStrategyFunction;
    unstable_patchRoutesOnMiss?: unstable_PatchRoutesOnMissFunction;
    window?: Window;
  }
): RemixRouter;

routes

An array of Route objects with nested routes on the children property.

createBrowserRouter([
  {
    path: "/",
    element: <Root />,
    loader: rootLoader,
    children: [
      {
        path: "events/:id",
        element: <Event />,
        loader: eventLoader,
      },
    ],
  },
]);

opts.basename

The basename of the app for situations where you can't deploy to the root of the domain, but a sub directory.

createBrowserRouter(routes, {
  basename: "/app",
});

The trailing slash will be respected when linking to the root:

createBrowserRouter(routes, {
  basename: "/app",
});
<Link to="/" />; // results in <a href="/app" />

createBrowserRouter(routes, {
  basename: "/app/",
});
<Link to="/" />; // results in <a href="/app/" />

opts.future

An optional set of Future Flags to enable for this Router. We recommend opting into newly released future flags sooner rather than later to ease your eventual migration to v7.

const router = createBrowserRouter(routes, {
  future: {
    // Normalize `useNavigation()`/`useFetcher()` `formMethod` to uppercase
    v7_normalizeFormMethod: true,
  },
});

The following future flags are currently available:

opts.hydrationData

When Server-Rendering and opting-out of automatic hydration, the hydrationData option allows you to pass in hydration data from your server-render. This will almost always be a subset of data from the StaticHandlerContext value you get back from handler.query:

const router = createBrowserRouter(routes, {
  hydrationData: {
    loaderData: {
      // [routeId]: serverLoaderData
    },
    // may also include `errors` and/or `actionData`
  },
});

Partial Hydration Data

You will almost always include a complete set of loaderData to hydrate a server-rendered app. But in advanced use-cases (such as Remix's clientLoader), you may want to include loaderData for only some routes that were rendered on the server. If you want to enable partial loaderData and opt-into granular route.HydrateFallback usage, you will need to enable the future.v7_partialHydration flag. Prior to this flag, any provided loaderData was assumed to be complete and would not result in the execution of route loaders on initial hydration.

When this flag is specified, loaders will run on initial hydration in 2 scenarios:

• No hydration data is provided
  • In these cases the HydrateFallback component will render on initial hydration
• The loader.hydrate property is set to true
  • This allows you to run the loader even if you did not render a fallback on initial hydration (i.e., to prime a cache with hydration data)

const router = createBrowserRouter(
  [
    {
      id: "root",
      loader: rootLoader,
      Component: Root,
      children: [
        {
          id: "index",
          loader: indexLoader,
          HydrateFallback: IndexSkeleton,
          Component: Index,
        },
      ],
    },
  ],
  {
    future: {
      v7_partialHydration: true,
    },
    hydrationData: {
      loaderData: {
        root: "ROOT DATA",
        // No index data provided
      },
    },
  }
);

opts.unstable_dataStrategy

This is a low-level API intended for advanced use-cases. This overrides React Router's internal handling of loader/action execution, and if done incorrectly will break your app code. Please use with caution and perform the appropriate testing.

This API is marked "unstable" so it is subject to breaking API changes in minor releases

By default, React Router is opinionated about how your data is loaded/submitted - and most notably, executes all of your loaders in parallel for optimal data fetching. While we think this is the right behavior for most use-cases, we realize that there is no "one size fits all" solution when it comes to data fetching for the wide landscape of application requirements.

The unstable_dataStrategy option gives you full control over how your loaders and actions are executed and lays the foundation to build in more advanced APIs such as middleware, context, and caching layers. Over time, we expect that we'll leverage this API internally to bring more first class APIs to React Router, but until then (and beyond), this is your way to add more advanced functionality for your applications data needs.

Type Declaration

interface DataStrategyFunction {
  (args: DataStrategyFunctionArgs): Promise<
    HandlerResult[]
  >;
}

interface DataStrategyFunctionArgs<Context = any> {
  request: Request;
  params: Params;
  context?: Context;
  matches: DataStrategyMatch[];
}

interface DataStrategyMatch
  extends AgnosticRouteMatch<
    string,
    AgnosticDataRouteObject
  > {
  shouldLoad: boolean;
  resolve: (
    handlerOverride?: (
      handler: (ctx?: unknown) => DataFunctionReturnValue
    ) => Promise<HandlerResult>
  ) => Promise<HandlerResult>;
}

interface HandlerResult {
  type: "data" | "error";
  result: any; // data, Error, Response, DeferredData
  status?: number;
}

Overview

unstable_dataStrategy receives the same arguments as a loader/action (request, params) but it also receives a matches array which is an array of the matched routes where each match is extended with 2 new fields for use in the data strategy function:

• match.resolve - An async function that will resolve any route.lazy implementations and execute the route's handler (if necessary), returning a HandlerResult
  • You should call match.resolve for all matches every time to ensure that all lazy routes are properly resolved
  • This does not mean you're calling the loader/action (the "handler") - resolve will only call the handler internally if needed and if you don't pass your own handlerOverride function parameter
  • See the examples below for how to implement custom handler execution via match.resolve
• match.shouldLoad - A boolean value indicating whether this route handler needs to be called in this pass
  • The matches array always includes all matched routes even when only some route handlers need to be called so that things like middleware can be implemented
  • shouldLoad is usually only interesting if you are skipping the route handler entirely and implementing custom handler logic - since it lets you determine if that custom logic should run for this route or not
  • For example:
    • If you are on /parent/child/a and you navigate to /parent/child/b - you'll get an array of three matches ([parent, child, b]), but only b will have shouldLoad=true because the data for parent and child is already loaded
    • If you are on /parent/child/a and you submit to a's action, then only a will have shouldLoad=true for the action execution of dataStrategy
      • After the action, dataStrategy will be called again for the loader revalidation, and all matches will have shouldLoad=true (assuming no custom shouldRevalidate implementations)

The dataStrategy function should return a parallel array of HandlerResult instances, which indicates if the handler was successful or not. If the returned handlerResult.result is a Response, React Router will unwrap it for you (via res.json or res.text). If you need to do custom decoding of a Response but preserve the status code, you can return the decoded value in handlerResult.result and send the status along via handlerResult.status (for example, when using the future.v7_skipActionRevalidation flag). match.resolve() will return a HandlerResult if you are not passing it a handler override function. If you are, then you need to wrap the handler result in a HandlerResult (see examples below).

Example Use Cases

Adding logging

In the simplest case, let's look at hooking into this API to add some logging for when our route loaders/actions execute:

let router = createBrowserRouter(routes, {
  unstable_dataStrategy({ request, matches }) {
    return Promise.all(
      matches.map(async (match) => {
        console.log(`Processing route ${match.route.id}`);
        // Don't override anything - just resolve route.lazy + call loader
        let result = await match.resolve();
        console.log(
          `Done processing route ${match.route.id}`
        );
        return result;
      })
    );
  },
});

Middleware

Let's define a middleware on each route via handle and call middleware sequentially first, then call all loaders in parallel - providing any data made available via the middleware:

const routes = [
  {
    id: "parent",
    path: "/parent",
    loader({ request }, context) {
      /*...*/
    },
    handle: {
      async middleware({ request }, context) {
        context.parent = "PARENT MIDDLEWARE";
      },
    },
    children: [
      {
        id: "child",
        path: "child",
        loader({ request }, context) {
          /*...*/
        },
        handle: {
          async middleware({ request }, context) {
            context.child = "CHILD MIDDLEWARE";
          },
        },
      },
    ],
  },
];

let router = createBrowserRouter(routes, {
  async unstable_dataStrategy({
    request,
    params,
    matches,
  }) {
    // Run middleware sequentially and let them add data to `context`
    let context = {};
    for (const match of matches) {
      if (match.route.handle?.middleware) {
        await match.route.handle.middleware(
          { request, params },
          context
        );
      }
    }

    // Run loaders in parallel with the `context` value
    return Promise.all(
      matches.map((match, i) =>
        match.resolve(async (handler) => {
          // Whatever you pass to `handler` will be passed as the 2nd parameter
          // to your loader/action
          let result = await handler(context);
          return { type: "data", result };
        })
      )
    );
  },
});

Custom Handler

It's also possible you don't even want to define a loader implementation at the route level. Maybe you want to just determine the routes and issue a single GraphQL request for all of your data? You can do that by setting your route.loader=true so it qualifies as "having a loader", and then store GQL fragments on route.handle:

const routes = [
  {
    id: "parent",
    path: "/parent",
    loader: true,
    handle: {
      gql: gql`
        fragment Parent on Whatever {
          parentField
        }
      `,
    },
    children: [
      {
        id: "child",
        path: "child",
        loader: true,
        handle: {
          gql: gql`
            fragment Child on Whatever {
              childField
            }
          `,
        },
      },
    ],
  },
];

let router = createBrowserRouter(routes, {
  unstable_dataStrategy({ request, params, matches }) {
    // Compose route fragments into a single GQL payload
    let gql = getFragmentsFromRouteHandles(matches);
    let data = await fetchGql(gql);
    // Parse results back out into individual route level HandlerResult's
    let results = parseResultsFromGql(data);
    return results;
  },
});

opts.unstable_patchRoutesOnMiss

This API is marked "unstable" so it is subject to breaking API changes in minor releases

By default, React Router wants you to provide a full route tree up front via createBrowserRouter(routes). This allows React Router to perform synchronous route matching, execute loaders, and then render route components in the most optimistic manner without introducing waterfalls. The tradeoff is that your initial JS bundle is larger by definition - which may slow down application start-up times as your application grows.

To combat this, we introduced route.lazy in v6.9.0 which let's you lazily load the route implementation (loader, Component, etc.) while still providing the route definition aspects up front (path, index, etc.). This is a good middle ground because React Router still knows about your routes up front and can perform synchronous route matching, but then delay loading any of the route implementation aspects until the route is actually navigated to.

In some cases, even this doesn't go far enough. For very large applications, providing all route definitions up front can be prohibitively expensive. Additionally, it might not even be possible to provide all route definitions up front in certain Micro-Frontend or Module-Federation architectures.

This is where unstable_patchRoutesOnMiss comes in (RFC). This API is for advanced use-cases where you are unable to provide the full route tree up-front and need a way to lazily "discover" portions of the route tree at runtime. This feature is often referred to as "Fog of War" because similar to how video games expand the "world" as you move around - the router would be expanding its routing tree as the user navigated around the app - but would only ever end up loading portions of the tree that the user visited.

Type Declaration

export interface unstable_PatchRoutesOnMissFunction {
  (opts: {
    path: string;
    matches: RouteMatch[];
    patch: (
      routeId: string | null,
      children: RouteObject[]
    ) => void;
  }): void | Promise<void>;
}

Overview

unstable_patchRoutesOnMiss will be called anytime React Router is unable to match a path. The arguments include the path, any partial matches, and a patch function you can call to patch new routes into the tree at a specific location. This method is executed during the loading portion of the navigation for GET requests and during the submitting portion of the navigation for non-GET requests.

Patching children into an existing route

const router = createBrowserRouter(
  [
    {
      id: "root",
      path: "/",
      Component: RootComponent,
    },
  ],
  {
    async unstable_patchRoutesOnMiss({ path, patch }) {
      if (path === "/a") {
        // Load/patch the `a` route as a child of the route with id `root`
        let route = await getARoute();
        //  ^ { path: 'a', Component: A }
        patch("root", [route]);
      }
    },
  }
);

In the above example, if the user clicks a link to /a, React Router won't be able to match it initially and will call patchRoutesOnMiss with /a and a matches array containing the root route match. By calling patch, the a route will be added to the route tree and React Router will perform matching again. This time it will successfully match the /a path and the navigation will complete successfully.

Patching new root-level routes

If you need to patch a new route to the top of the tree (i.e., it doesn't have a parent), you can pass null as the routeId:

const router = createBrowserRouter(
  [
    {
      id: "root",
      path: "/",
      Component: RootComponent,
    },
  ],
  {
    async unstable_patchRoutesOnMiss({ path, patch }) {
      if (path === "/root-sibling") {
        // Load/patch the `/root-sibling` route as a sibling of the root route
        let route = await getRootSiblingRoute();
        //  ^ { path: '/root-sibling', Component: RootSibling }
        patch(null, [route]);
      }
    },
  }
);

Patching sub-trees asyncronously

You can also perform asynchronous matching to lazily fetch entire sections of your application:

let router = createBrowserRouter(
  [
    {
      path: "/",
      Component: Home,
    },
  ],
  {
    async unstable_patchRoutesOnMiss({ path, patch }) {
      if (path.startsWith("/dashboard")) {
        let children = await import("./dashboard");
        patch(null, children);
      }
      if (path.startsWith("/account")) {
        let children = await import("./account");
        patch(null, children);
      }
    },
  }
);

Co-locating route discovery with route definition

If you don't wish to perform your own pseudo-matching, you can leverage the partial matches array and the handle field on a route to keep the children definitions co-located:

let router = createBrowserRouter(
  [
    {
      path: "/",
      Component: Home,
    },
    {
      path: "/dashboard",
      children: [
        {
          // If we want to include /dashboard in the critical routes, we need to
          // also include it's index route since patchRoutesOnMiss will not be
          // called on a navigation to `/dashboard` because it will have successfully
          // matched the `/dashboard` parent route
          index: true,
          // ...
        },
      ],
      handle: {
        lazyChildren: () => import("./dashboard"),
      },
    },
    {
      path: "/account",
      children: [
        {
          index: true,
          // ...
        },
      ],
      handle: {
        lazyChildren: () => import("./account"),
      },
    },
  ],
  {
    async unstable_patchRoutesOnMiss({ matches, patch }) {
      let leafRoute = matches[matches.length - 1]?.route;
      if (leafRoute?.handle?.lazyChildren) {
        let children =
          await leafRoute.handle.lazyChildren();
        patch(leafRoute.id, children);
      }
    },
  }
);

opts.window

Useful for environments like browser devtool plugins or testing to use a different window than the global window.