jutsu-bun:bun-runtime

Bun.serve enables ultra-fast HTTP server creation with native APIs. Use Bun.serve to define request handlers, specify port and hostname, and serve connections. It supports WebSocket upgrades and handles concurrent requests efficiently without external dependencies.

File I/O in Bun uses Bun.file for reads and Bun.write for writes, optimized for performance. Bun.file returns a file object with text(), json(), and arrayBuffer() methods; Bun.write accepts strings, buffers, or typed arrays and overwrites or appends to disk in a single operation.

Bun.env provides type-safe environment variable access at runtime. Reference variables as properties (Bun.env.VAR_NAME) rather than string keys to enable TypeScript checking and prevent undefined access errors in production workflows.

Bun.$ executes shell commands inline within JavaScript. Pass command strings or template literals to Bun.$, capture stdout and stderr as promises, and integrate shell output into file-processing or API workflows without spawning separate processes.

Bun.serve includes built-in WebSocket support via the upgrade handler. Define an upgrade function in your server config to handle WebSocket connections, enabling real-time bidirectional communication alongside standard HTTP routes.