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The --hot flag runs a file with hot reloading enabled. When any module or file changes, Bun re-runs the file.
terminal
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.
Hot reloading doesn’t reload the page in your browser.
https://mintcdn.com/bun-1dd33a4e/JUhaF6Mf68z_zHyy/icons/typescript.svg?fit=max&auto=format&n=JUhaF6Mf68z_zHyy&q=85&s=7ac549adaea8d5487d8fbd58cc3ea35bindex.ts
Bun.serve({
  port: 3000,
  fetch(req) {
    return new Response("Hello world");
  },
});