# Remix > Builds full-stack React applications with Remix using loaders, actions, nested routes, and progressive enhancement. Use when creating Remix projects, implementing data loading, form handling, error boundaries, or deploying to various platforms. - Skill: `majiayu000/remix` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds add majiayu000/remix` - Raw SKILL.md: https://api.skillmd.com/api/skills/majiayu000/remix/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Web & Frontend - Author: majiayu000 (https://skillmd.com/u/majiayu000) - Updated: 2026-09-09 - Page: https://skillmd.com/skills/majiayu000/remix --- # Remix Full-stack React framework with nested routing, server-side data loading, progressive enhancement, and bring-your-own-server flexibility. ## Quick Start **Create new project:** ```bash npx create-remix@latest my-app cd my-app npm run dev ``` **Manual setup:** ```bash mkdir my-remix-app && cd my-remix-app npm init -y npm i @remix-run/node @remix-run/react @remix-run/serve isbot react react-dom npm i -D @remix-run/dev vite typescript @types/react @types/react-dom ``` **Essential file structure:** ``` app/ root.tsx # Root layout (required) routes/ _index.tsx # Home page (/) about.tsx # /about posts.$slug.tsx # /posts/:slug entry.client.tsx # Client entry entry.server.tsx # Server entry vite.config.ts ``` ## File-Based Routing ### Route Conventions | File | Route | |------|-------| | `_index.tsx` | `/` (index route) | | `about.tsx` | `/about` | | `posts._index.tsx` | `/posts` | | `posts.$slug.tsx` | `/posts/:slug` | | `posts.$slug_.edit.tsx` | `/posts/:slug/edit` (escaping nesting) | | `$.tsx` | Splat (catch-all) | ### Special Characters | Character | Purpose | Example | |-----------|---------|---------| | `.` | Nested URL segment | `posts.new.tsx` -> `/posts/new` | | `$` | Dynamic segment | `posts.$id.tsx` -> `/posts/:id` | | `_` | Layout nesting escape | `posts_.$id.tsx` -> no layout | | `()` | Optional segment | `($lang).about.tsx` | ### Nested Routes ``` app/routes/ dashboard.tsx # Layout for /dashboard/* dashboard._index.tsx # /dashboard dashboard.settings.tsx # /dashboard/settings dashboard.users.tsx # /dashboard/users ``` ```tsx // app/routes/dashboard.tsx (Layout) import { Outlet } from "@remix-run/react"; export default function DashboardLayout() { return (

{/* Child routes render here */}

); } ``` ## Root Route ```tsx // app/root.tsx import { Links, Meta, Outlet, Scripts, ScrollRestoration, } from "@remix-run/react"; export function Layout({ children }: { children: React.ReactNode }) { return ( {children} ); } export default function App() { return ; } ``` ## Loaders (Data Fetching) ### Basic Loader ```tsx // app/routes/posts._index.tsx import { json } from "@remix-run/node"; import { useLoaderData } from "@remix-run/react"; import type { LoaderFunctionArgs } from "@remix-run/node"; export const loader = async ({ request }: LoaderFunctionArgs) => { const posts = await db.posts.findMany(); return json({ posts }); }; export default function Posts() { const { posts } = useLoaderData(); return (

{post.title}

); } ``` ### With Parameters ```tsx // app/routes/posts.$slug.tsx import { json } from "@remix-run/node"; import type { LoaderFunctionArgs } from "@remix-run/node"; export const loader = async ({ params }: LoaderFunctionArgs) => { const post = await db.posts.findUnique({ where: { slug: params.slug }, }); if (!post) { throw new Response("Not Found", { status: 404 }); } return json({ post }); }; ``` ### With Search Params ```tsx export const loader = async ({ request }: LoaderFunctionArgs) => { const url = new URL(request.url); const query = url.searchParams.get("q") ?? ""; const page = Number(url.searchParams.get("page")) || 1; const posts = await db.posts.findMany({ where: { title: { contains: query } }, skip: (page - 1) * 10, take: 10, }); return json({ posts, query, page }); }; ``` ### With Headers ```tsx export const loader = async ({ request }: LoaderFunctionArgs) => { const authHeader = request.headers.get("Authorization"); // Check auth if (!authHeader) { throw new Response("Unauthorized", { status: 401 }); } return json({ data: "secret" }); }; ``` ## Actions (Mutations) ### Basic Form Action ```tsx // app/routes/posts.new.tsx import { json, redirect } from "@remix-run/node"; import { Form, useActionData } from "@remix-run/react"; import type { ActionFunctionArgs } from "@remix-run/node"; export const action = async ({ request }: ActionFunctionArgs) => { const formData = await request.formData(); const title = formData.get("title") as string; const content = formData.get("content") as string; // Validate const errors: Record = {}; if (!title) errors.title = "Title is required"; if (!content) errors.content = "Content is required"; if (Object.keys(errors).length > 0) { return json({ errors }, { status: 400 }); } // Create post await db.posts.create({ data: { title, content } }); return redirect("/posts"); }; export default function NewPost() { const actionData = useActionData(); return (

Title {actionData?.errors?.title && (

{actionData.errors.title}

)}

Content

</label>
        {actionData?.errors?.content && (
          <p className="error">{actionData.errors.content}</p>
        )}
      </div>

<button type="submit">Create Post</button>
    </Form>
  );
}
```

### Multiple Actions (Intent Pattern)

```tsx
export const action = async ({ request }: ActionFunctionArgs) => {
  const formData = await request.formData();
  const intent = formData.get("intent");

switch (intent) {
    case "create":
      return createItem(formData);
    case "update":
      return updateItem(formData);
    case "delete":
      return deleteItem(formData);
    default:
      throw new Response("Invalid intent", { status: 400 });
  }
};

// In component
<Form method="post">
  <input type="hidden" name="id" value={item.id} />
  <button type="submit" name="intent" value="update">Update</button>
  <button type="submit" name="intent" value="delete">Delete</button>
</Form>
```

## Forms

### Form Component

```tsx
import { Form } from "@remix-run/react";

// POST to current route
<Form method="post">
  <input name="email" type="email" />
  <button type="submit">Submit</button>
</Form>

// POST to different route
<Form method="post" action="/subscribe">
  <input name="email" type="email" />
  <button type="submit">Subscribe</button>
</Form>

// GET (search)
<Form method="get" action="/search">
  <input name="q" type="search" />
  <button type="submit">Search</button>
</Form>
```

### Pending States

```tsx
import { Form, useNavigation } from "@remix-run/react";

export default function CreatePost() {
  const navigation = useNavigation();
  const isSubmitting = navigation.state === "submitting";

return (
    <Form method="post">
      <input name="title" disabled={isSubmitting} />
      <button type="submit" disabled={isSubmitting}>
        {isSubmitting ? "Creating..." : "Create"}
      </button>
    </Form>
  );
}
```

### useFetcher (Non-Navigation Mutations)

```tsx
import { useFetcher } from "@remix-run/react";

export function LikeButton({ postId }: { postId: string }) {
  const fetcher = useFetcher();
  const isLiking = fetcher.state === "submitting";

return (
    <fetcher.Form method="post" action="/api/like">
      <input type="hidden" name="postId" value={postId} />
      <button type="submit" disabled={isLiking}>
        {isLiking ? "..." : "Like"}
      </button>
    </fetcher.Form>
  );
}
```

### Optimistic UI

```tsx
export function TodoItem({ todo }) {
  const fetcher = useFetcher();

// Optimistic value
  const isCompleted = fetcher.formData
    ? fetcher.formData.get("completed") === "true"
    : todo.completed;

return (
    <fetcher.Form method="post">
      <input type="hidden" name="id" value={todo.id} />
      <input
        type="checkbox"
        name="completed"
        value="true"
        checked={isCompleted}
        onChange={(e) => fetcher.submit(e.target.form)}
      />
      <span className={isCompleted ? "line-through" : ""}>
        {todo.title}
      </span>
    </fetcher.Form>
  );
}
```

## Error Handling

### Error Boundary

```tsx
// app/routes/posts.$slug.tsx
import { useRouteError, isRouteErrorResponse } from "@remix-run/react";

export function ErrorBoundary() {
  const error = useRouteError();

if (isRouteErrorResponse(error)) {
    return (
      <div>
        <h1>{error.status} {error.statusText}</h1>
        <p>{error.data}</p>
      </div>
    );
  }

return (
    <div>
      <h1>Error</h1>
      <p>{error instanceof Error ? error.message : "Unknown error"}</p>
    </div>
  );
}
```

### Throwing Responses

```tsx
export const loader = async ({ params }: LoaderFunctionArgs) => {
  const post = await db.posts.findUnique({ where: { slug: params.slug } });

if (!post) {
    throw new Response("Post not found", { status: 404 });
  }

return json({ post });
};
```

## Meta & Links

### Meta Tags

```tsx
import type { MetaFunction } from "@remix-run/node";

// Static meta
export const meta: MetaFunction = () => {
  return [
    { title: "My Page" },
    { name: "description", content: "Page description" },
  ];
};

// Dynamic meta from loader
export const meta: MetaFunction<typeof loader> = ({ data }) => {
  return [
    { title: data?.post.title ?? "Post" },
    { name: "description", content: data?.post.excerpt },
  ];
};
```

### Links (CSS, Fonts)

```tsx
import type { LinksFunction } from "@remix-run/node";
import styles from "~/styles/app.css?url";

export const links: LinksFunction = () => [
  { rel: "stylesheet", href: styles },
  { rel: "preconnect", href: "https://fonts.googleapis.com" },
];
```

## Resource Routes (API)

```tsx
// app/routes/api.posts.tsx
import { json } from "@remix-run/node";
import type { LoaderFunctionArgs, ActionFunctionArgs } from "@remix-run/node";

// GET /api/posts
export const loader = async ({ request }: LoaderFunctionArgs) => {
  const posts = await db.posts.findMany();
  return json(posts);
};

// POST /api/posts
export const action = async ({ request }: ActionFunctionArgs) => {
  const body = await request.json();
  const post = await db.posts.create({ data: body });
  return json(post, { status: 201 });
};
```

## Streaming (Deferred Data)

```tsx
import { defer } from "@remix-run/node";
import { Await, useLoaderData } from "@remix-run/react";
import { Suspense } from "react";

export const loader = async () => {
  // Fast data - awaited
  const criticalData = await getCriticalData();

// Slow data - deferred
  const slowDataPromise = getSlowData();

return defer({
    criticalData,
    slowData: slowDataPromise,
  });
};

export default function Page() {
  const { criticalData, slowData } = useLoaderData<typeof loader>();

return (
    <div>
      <h1>{criticalData.title}</h1>

<Suspense fallback={<p>Loading...</p>}>
        <Await resolve={slowData}>
          {(data) => <SlowComponent data={data} />}
        </Await>
      </Suspense>
    </div>
  );
}
```

## Sessions & Cookies

```tsx
// app/sessions.server.ts
import { createCookieSessionStorage } from "@remix-run/node";

export const sessionStorage = createCookieSessionStorage({
  cookie: {
    name: "__session",
    httpOnly: true,
    maxAge: 60 * 60 * 24 * 7, // 1 week
    path: "/",
    sameSite: "lax",
    secrets: [process.env.SESSION_SECRET!],
    secure: process.env.NODE_ENV === "production",
  },
});

export const { getSession, commitSession, destroySession } = sessionStorage;
```

```tsx
// Usage in loader/action
import { getSession, commitSession } from "~/sessions.server";

export const action = async ({ request }: ActionFunctionArgs) => {
  const session = await getSession(request.headers.get("Cookie"));
  session.set("userId", user.id);

return redirect("/dashboard", {
    headers: {
      "Set-Cookie": await commitSession(session),
    },
  });
};

export const loader = async ({ request }: LoaderFunctionArgs) => {
  const session = await getSession(request.headers.get("Cookie"));
  const userId = session.get("userId");

if (!userId) {
    throw redirect("/login");
  }

return json({ user: await getUser(userId) });
};
```

## Common Patterns

### Protected Routes

```tsx
// app/utils/auth.server.ts
export async function requireUser(request: Request) {
  const session = await getSession(request.headers.get("Cookie"));
  const userId = session.get("userId");

if (!userId) {
    throw redirect("/login");
  }

const user = await db.users.findUnique({ where: { id: userId } });

if (!user) {
    throw redirect("/login");
  }

return user;
}

// In route
export const loader = async ({ request }: LoaderFunctionArgs) => {
  const user = await requireUser(request);
  return json({ user });
};
```

### Flash Messages

```tsx
export const action = async ({ request }: ActionFunctionArgs) => {
  const session = await getSession(request.headers.get("Cookie"));
  session.flash("success", "Post created successfully!");

return redirect("/posts", {
    headers: {
      "Set-Cookie": await commitSession(session),
    },
  });
};

export const loader = async ({ request }: LoaderFunctionArgs) => {
  const session = await getSession(request.headers.get("Cookie"));
  const message = session.get("success");

return json(
    { message },
    {
      headers: {
        "Set-Cookie": await commitSession(session),
      },
    }
  );
};
```

## Best Practices

1. **Colocate data with UI** - Keep loaders/actions in the same file as components
2. **Use Form over fetch** - Progressive enhancement by default
3. **Throw responses for errors** - Triggers error boundaries
4. **Use resource routes for APIs** - Not everything needs UI
5. **Defer slow data** - Stream non-critical content
6. **Validate on server** - Never trust client data

## Common Mistakes

| Mistake | Fix |
|---------|-----|
| Fetching in useEffect | Use loaders instead |
| Using fetch for mutations | Use Form/useFetcher |
| Not handling loading states | Check navigation.state |
| Forgetting error boundaries | Add ErrorBoundary export |
| Client-side state for server data | Use loader + revalidation |

## Reference Files

- [references/routing.md](references/routing.md) - Advanced routing patterns
- [references/data-flow.md](references/data-flow.md) - Loaders, actions, and revalidation
- [references/deployment.md](references/deployment.md) - Deployment to various platforms

## Templates

- [templates/route.tsx](templates/route.tsx) - Standard route template
- [templates/resource-route.ts](templates/resource-route.ts) - API route template