bun-types

As of Bun v1.1.44, we've added initial support for bundling frontend apps directly in Bun's HTTP server: `Bun.serve()`. Run your frontend and backend in the same app with no extra steps. To get started, import your HTML files and pass them to the `static` option in `Bun.serve()`. ```ts import dashboard from "./dashboard.html"; import homepage from "./index.html"; const server = Bun.serve({ // Add HTML imports to `static` static: { // Bundle & route index.html to "/" "/": homepage, // Bundle & route dashboard.html to "/dashboard" "/dashboard": dashboard, }, // Enable development mode for: // - Detailed error messages // - Rebuild on request development: true, // Handle API requests async fetch(req) { // ...your API code if (req.url.endsWith("/api/users")) { const users = await Bun.sql`SELECT * FROM users`; return Response.json(users); } // Return 404 for unmatched routes return new Response("Not Found", { status: 404 }); }, }); console.log(`Listening on ${server.url}`) ``` ```bash $ bun run app.ts ``` ## HTML imports are routes The web starts with HTML, and so does Bun's fullstack dev server. To specify entrypoints to your frontend, import HTML files into your JavaScript/TypeScript/TSX/JSX files. ```ts import dashboard from "./dashboard.html"; import homepage from "./index.html"; ``` These HTML files are used as routes in Bun's dev server you can pass to `Bun.serve()`. ```ts Bun.serve({ static: { "/": homepage, "/dashboard": dashboard, } fetch(req) { // ... api requests }, }); ``` When you make a request to `/dashboard` or `/`, Bun automatically bundles the `<script>` and `<link>` tags in the HTML files, exposes them as static routes, and serves the result. An index.html file like this: ```html#index.html <!DOCTYPE html> <html> <head> <title>Home</title> <link rel="stylesheet" href="./reset.css" /> <link rel="stylesheet" href="./styles.css" /> </head> <body> <div id="root"></div> <script type="module" src="./sentry-and-preloads.ts"></script> <script type="module" src="./my-app.tsx"></script> </body> </html> ``` Becomes something like this: ```html#index.html <!DOCTYPE html> <html> <head> <title>Home</title> <link rel="stylesheet" href="/index-[hash].css" /> </head> <body> <div id="root"></div> <script type="module" src="/index-[hash].js"></script> </body> </html> ``` ### How to use with React To use React in your client-side code, import `react-dom/client` and render your app. {% codetabs %} ```ts#src/backend.ts import dashboard from "../public/dashboard.html"; import { serve } from "bun"; serve({ static: { "/": dashboard, }, async fetch(req) { // ...api requests return new Response("hello world"); }, }); ``` ```ts#src/frontend.tsx import "./styles.css"; import { createRoot } from "react-dom/client"; import { App } from "./app.tsx"; document.addEventListener("DOMContentLoaded", () => { const root = createRoot(document.getElementById("root")); root.render(<App />); }); ``` ```html#public/dashboard.html <!DOCTYPE html> <html> <head> <title>Dashboard</title> </head> <body> <div id="root"></div> <script type="module" src="../src/frontend.tsx"></script> </body> </html> ``` ```css#src/styles.css body { background-color: red; } ``` ```tsx#src/app.tsx export function App() { return <div>Hello World</div>; } ``` {% /codetabs %} ### Development mode When building locally, enable development mode by setting `development: true` in `Bun.serve()`. ```js-diff import homepage from "./index.html"; import dashboard from "./dashboard.html"; Bun.serve({ static: { "/": homepage, "/dashboard": dashboard, } + development: true, fetch(req) { // ... api requests }, }); ``` When `development` is `true`, Bun will: - Include the `SourceMap` header in the response so that devtools can show the original source code - Disable minification - Re-bundle assets on each request to a .html file #### Production mode When serving your app in production, set `development: false` in `Bun.serve()`. - Enable in-memory caching of bundled assets. Bun will bundle assets lazily on the first request to an `.html` file, and cache the result in memory until the server restarts. - Enables `Cache-Control` headers and `ETag` headers - Minifies JavaScript/TypeScript/TSX/JSX files ## Plugins Bun's [bundler plugins](https://bun.sh/docs/bundler/plugins) are also supported when bundling static routes. To configure plugins for `Bun.serve`, add a `plugins` array in the `[serve.static]` section of your `bunfig.toml`. ### Using TailwindCSS in HTML routes For example, enable TailwindCSS on your routes by installing and adding the `bun-plugin-tailwind` plugin: ```sh $ bun add bun-plugin-tailwind ``` ```toml#bunfig.toml [serve.static] plugins = ["bun-plugin-tailwind"] ``` This will allow you to use TailwindCSS utility classes in your HTML and CSS files. All you need to do is import `tailwindcss` somewhere: ```html#index.html <!doctype html> <html> <head> <title>Home</title> <link rel="stylesheet" href="tailwindcss" /> </head> <body>  </body> </html> ``` Or in your CSS: ```css#style.css @import "tailwindcss"; ``` ### Custom plugins Any JS file or module which exports a [valid bundler plugin object](https://bun.sh/docs/bundler/plugins#usage) (essentially an object with a `name` and `setup` field) can be placed inside the `plugins` array: ```toml#bunfig.toml [serve.static] plugins = ["./my-plugin-implementation.ts"] ``` Bun will lazily resolve and load each plugin and use them to bundle your routes. ## How this works Bun uses [`HTMLRewriter`](/docs/api/html-rewriter) to scan for `<script>` and `<link>` tags in HTML files, uses them as entrypoints for [Bun's bundler](/docs/bundler), generates an optimized bundle for the JavaScript/TypeScript/TSX/JSX and CSS files, and serves the result. 1. **`<script>` processing** - Transpiles TypeScript, JSX, and TSX in `<script>` tags - Bundles imported dependencies - Generates sourcemaps for debugging - Minifies when `development` is not `true` in `Bun.serve()` ```html <script type="module" src="./counter.tsx"></script> ``` 2. **`<link>` processing** - Processes CSS imports and `<link>` tags - Concatenates CSS files - Rewrites `url` and asset paths to include content-addressable hashes in URLs ```html <link rel="stylesheet" href="./styles.css" /> ``` 3. **`<img>` & asset processing** - Links to assets are rewritten to include content-addressable hashes in URLs - Small assets in CSS files are inlined into `data:` URLs, reducing the total number of HTTP requests sent over the wire 4. **Rewrite HTML** - Combines all `<script>` tags into a single `<script>` tag with a content-addressable hash in the URL - Combines all `<link>` tags into a single `<link>` tag with a content-addressable hash in the URL - Outputs a new HTML file 5. **Serve** - All the output files from the bundler are exposed as static routes, using the same mechanism internally as when you pass a `Response` object to [`static` in `Bun.serve()`](/docs/api/http#static-routes). This works similarly to how [`Bun.build` processes HTML files](/docs/bundler/html). ## This is a work in progress - Client-side hot reloading isn't wired up yet. It will be in the future. - This doesn't support `bun build` yet. It also will in the future.