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Let's write a simple HTTP server using the built-in `Bun.serve` API. First, create a fresh directory.
```bash
$ mkdir quickstart
$ cd quickstart
```
Run `bun init` to scaffold a new project. It's an interactive tool; for this tutorial, just press `enter` to accept the default answer for each prompt.
```bash
$ bun init
bun init helps you get started with a minimal project and tries to
guess sensible defaults. Press ^C anytime to quit.
package name (quickstart):
entry point (index.ts):
Done! A package.json file was saved in the current directory.
+ index.ts
+ .gitignore
+ tsconfig.json (for editor auto-complete)
+ README.md
To get started, run:
bun run index.ts
```
Since our entry point is a `*.ts` file, Bun generates a `tsconfig.json` for you. If you're using plain JavaScript, it will generate a [`jsconfig.json`](https://code.visualstudio.com/docs/languages/jsconfig) instead.
## Run a file
Open `index.ts` and paste the following code snippet, which implements a simple HTTP server with [`Bun.serve`](/docs/api/http).
```ts
const server = Bun.serve({
port: 3000,
fetch(req) {
return new Response("Bun!");
},
});
console.log(`Listening on http://localhost:${server.port} ...`);
```
<!--
### TypeScript
If you're using TypeScript, you may see a type error on the `Bun` global. To fix this, install `bun-types`.
```sh
$ bun add -d bun-types
```
Then add the following line to your `compilerOptions` in `tsconfig.json`.
```json-diff#tsconfig.json
{
"compilerOptions": {
+ "types": ["bun-types"]
}
}
``` -->
Run the file from your shell.
```bash
$ bun index.ts
Listening on http://localhost:3000 ...
```
Visit [http://localhost:3000](http://localhost:3000) to test the server. You should see a simple page that says "Bun!".
## Run a script
Bun can also execute `"scripts"` from your `package.json`. Add the following script:
```json-diff
{
"name": "quickstart",
"module": "index.ts",
"type": "module",
+ "scripts": {
+ "start": "bun run index.ts"
+ },
"devDependencies": {
"bun-types": "^0.7.0"
}
}
```
Then run it with `bun run start`.
```bash
$ bun run start
$ bun run index.ts
Listening on http://localhost:3000 ...
```
{% callout %}
⚡️ **Performance** — `bun run` is roughly 28x faster than `npm run` (6ms vs 170ms of overhead).
{% /callout %}
## Install a package
Let's make our server a little more interesting by installing a package. First install the `figlet` package and its type declarations. Figlet is a utility for converting strings into ASCII art.
```bash
$ bun add figlet
$ bun add -d @types/figlet # TypeScript users only
```
Update `index.ts` to use `figlet` in the `fetch` handler.
```ts-diff
+ import figlet from "figlet";
const server = Bun.serve({
fetch() {
+ const body = figlet.textSync("Bun!");
+ return new Response(body);
- return new Response("Bun!");
},
port: 3000,
});
```
Restart the server and refresh the page. You should see a new ASCII art banner.
```txt
____ _
| __ ) _ _ _ __ | |
| _ \| | | | '_ \| |
| |_) | |_| | | | |_|
|____/ \__,_|_| |_(_)
```
|
