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Hot reload an HTTP server with Bun

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Bun supports the --hot flag to run a file with hot reloading enabled. When any module or file changes, Bun re-runs the file.

bun --hot run index.ts

Bun detects when you are running an HTTP server with Bun.serve(). It reloads your fetch handler when source files change, without restarting the bun process. This makes hot reloads nearly instantaneous.

Bun.serve({
  port: 3000,
  fetch(req) {
    return new Response(`Hello world`);
  },
});

HTTP

Common HTTP server usage

Hot reload an HTTP server

Write a simple HTTP server

Configure TLS on an HTTP server

Send an HTTP request using fetch

Stream a file as an HTTP Response

Upload files via HTTP using FormData

fetch with unix domain sockets in Bun

Streaming HTTP Server with Async Iterators

Streaming HTTP Server with Node.js Streams

Package manager

Add a dependency

Add a Git dependency

Add a peer dependency

Add a tarball dependency

Add a trusted dependency

Add an optional dependency

Add a development dependency

Using bun install with Artifactory

Generate a human-readable lockfile

Configuring a monorepo using workspaces

Install a package under a different name

Install dependencies with Bun in GitHub Actions

Override the default npm registry for bun install

Using bun install with an Azure Artifacts npm registry

Configure a private registry for an organization scope with bun install

Processes

Read from stdin

Listen for CTRL+C

Listen to OS signals

Spawn a child process

Parse command-line arguments

Read stderr from a child process

Read stdout from a child process

Get the process uptime in nanoseconds

Spawn a child process and communicate using IPC

Reading files

Read a JSON file

Check if a file exists

Read a file to a Buffer

Read a file as a string

Get the MIME type of a file

Read a file to a Uint8Array

Read a file to an ArrayBuffer

Watch a directory for changes

Read a file as a ReadableStream

Runtime

Import a JSON file

Import a TOML file

Run a Shell Command

Re-map import paths

Set a time zone in Bun

Import HTML file as text

Set environment variables

Read environment variables

Debugging Bun with the web debugger

Install and run Bun in GitHub Actions

Install TypeScript declarations for Bun

Debugging Bun with the VS Code extension

Define and replace static globals & constants

Streams

Convert a ReadableStream to JSON

Convert a Node.js Readable to JSON

Convert a ReadableStream to a Blob

Convert a Node.js Readable to a Blob

Convert a ReadableStream to a Buffer

Convert a ReadableStream to a string

Convert a Node.js Readable to a string

Convert a ReadableStream to a Uint8Array

Convert a ReadableStream to an ArrayBuffer

Convert a Node.js Readable to an ArrayBuffer

Convert a ReadableStream to an array of chunks

Test runner

Mock functions in bun test

Spy on methods in bun test

Update snapshots in bun test

Run tests in watch mode with Bun

Use snapshot testing in bun test

Bail early with the Bun test runner

Skip tests with the Bun test runner

Migrate from Jest to Bun's test runner

Run your tests with the Bun test runner

Set the system time in Bun's test runner

Write browser DOM tests with Bun and happy-dom

Set a per-test timeout with the Bun test runner

Mark a test as a "todo" with the Bun test runner

Re-run tests multiple times with the Bun test runner

Set a code coverage threshold with the Bun test runner

Generate code coverage reports with the Bun test runner

Utilities

Hash a password

Escape an HTML string

Get the current Bun version

Encode and decode base64 strings

Check if two objects are deeply equal

Detect when code is executed with Bun

Get the directory of the current file

Get the file name of the current file

Convert a file URL to an absolute path

Compress and decompress data with gzip

Convert an absolute path to a file URL

Get the path to an executable bin file

Sleep for a fixed number of milliseconds

Compress and decompress data with DEFLATE

Get the absolute path of the current file

Check if the current file is the entrypoint

Get the absolute path to the current entrypoint

WebSocket

Build a simple WebSocket server

Enable compression for WebSocket messages

Build a publish-subscribe WebSocket server

Set per-socket contextual data on a WebSocket

Writing files

Write to stdout

Write a Blob to a file

Write a file to stdout

Append content to a file

Write a string to a file

Write a file incrementally

Write a Response to a file

Copy a file to another location

Write a ReadableStream to a file