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Bun 1.0 just launched and I'm genuinely impressed and intrigued. How long can this madness keep going? \nI've never built anything substantial with Bun. Just various scripts to get a feel for it.

At work, I recently launched a micro-service that uses Node + Fastify + TypeScript. I'm not going to rewrite it in Bun, but I'm going to get a feel for the difference.

Basic version in Bun

No need for a package.json at this point. And that's neat. Create a src/index.ts and put this in:

\nconst PORT = parseInt(process.env.PORT || "3000");\n\nBun.serve({\n  port: PORT,\n  fetch(req) {\n    const url = new URL(req.url);\n    if (url.pathname === "/") return new Response(`Home page!`);\n    if (url.pathname === "/json") return Response.json({ hello: "world" });\n    return new Response(`404!`);\n  },\n});\nconsole.log(`Listening on port ${PORT}`);\n\n

\n\n

What's so cool about the convenience-oriented developer experience of Bun is that it comes with a native way for restarting the server as you're editing the server code:

\n❯ bun --hot src/index.ts\nListening on port 3000\n

\n\n

Let's test it:

\n❯ xh http://localhost:3000/\nHTTP/1.1 200 OK\nContent-Length: 10\nContent-Type: text/plain;charset=utf-8\nDate: Sat, 09 Sep 2023 02:34:29 GMT\n\nHome page!\n\n❯ xh http://localhost:3000/json\nHTTP/1.1 200 OK\nContent-Length: 17\nContent-Type: application/json;charset=utf-8\nDate: Sat, 09 Sep 2023 02:34:35 GMT\n\n{\n    "hello": "world"\n}\n

\n\n

Basic version with Node + Fastify + TypeScript

First of all, you'll need to create a package.json to install the dependencies, all of which, at this gentle point are built into Bun:

\n❯ npm i -D ts-node typescript @types/node nodemon\n❯ npm i fastify\n

\n\n

And edit the package.json with some scripts:

\n  "scripts": {\n    "dev": "nodemon src/index.ts",\n    "start": "ts-node src/index.ts"\n  },\n

\n\n

And of course, the code itself (src/index.ts):

\nimport fastify from "fastify";\n\nconst PORT = parseInt(process.env.PORT || "3000");\n\nconst server = fastify();\n\nserver.get("/", async () => {\n  return "Home page!";\n});\n\nserver.get("/json", (request, reply) => {\n  reply.send({ hello: "world" });\n});\n\nserver.listen({ port: PORT }, (err, address) => {\n  if (err) {\n    console.error(err);\n    process.exit(1);\n  }\n  console.log(`Server listening at ${address}`);\n});\n

\n\n

Now run it:

\n❯ npm run dev\n\n> fastify-hello-world@1.0.0 dev\n> nodemon src/index.ts\n\n[nodemon] 3.0.1\n[nodemon] to restart at any time, enter `rs`\n[nodemon] watching path(s): *.*\n[nodemon] watching extensions: ts,json\n[nodemon] starting `ts-node src/index.ts`\nServer listening at http://[::1]:3000\n

\n\n

Let's test it:

\n❯ xh http://localhost:3000/\nHTTP/1.1 200 OK\nConnection: keep-alive\nContent-Length: 10\nContent-Type: text/plain; charset=utf-8\nDate: Sat, 09 Sep 2023 02:42:46 GMT\nKeep-Alive: timeout=72\n\nHome page!\n\n❯ xh http://localhost:3000/json\nHTTP/1.1 200 OK\nConnection: keep-alive\nContent-Length: 17\nContent-Type: application/json; charset=utf-8\nDate: Sat, 09 Sep 2023 02:43:08 GMT\nKeep-Alive: timeout=72\n\n{\n    "hello": "world"\n}\n

\n\n

For the record, I quite like this little setup. nodemon can automatically understand TypeScript. It's a neat minimum if Node is a desire.

Quick benchmark

Bun

Note that this server has no logging or any I/O.

\n❯ bun src/index.ts\nListening on port 3000\n

\n\n

Using hey to test 10,000 requests across 100 concurrent clients:

❯ hey -n 10000 -c 100 http://localhost:3000/\n\nSummary:\n  Total:    0.2746 secs\n  Slowest:  0.0167 secs\n  Fastest:  0.0002 secs\n  Average:  0.0026 secs\n  Requests/sec: 36418.8132\n\n  Total data:   100000 bytes\n  Size/request: 10 bytes

\n\n

Node + Fastify

\n❯ npm run start\n

\n\n

Using hey again:

❯ hey -n 10000 -c 100 http://localhost:3000/\n\nSummary:\n  Total:    0.6606 secs\n  Slowest:  0.0483 secs\n  Fastest:  0.0001 secs\n  Average:  0.0065 secs\n  Requests/sec: 15138.5719\n\n  Total data:   100000 bytes\n  Size/request: 10 bytes

\n\n

About a 2x advantage to Bun.

Serving an HTML file with Bun

\nBun.serve({\n  port: PORT,\n  fetch(req) {\n    const url = new URL(req.url);\n    if (url.pathname === "/") return new Response(`Home page!`);\n    if (url.pathname === "/json") return Response.json({ hello: "world" });\n+   if (url.pathname === "/index.html")\n+     return new Response(Bun.file("src/index.html"));\n    return new Response(`404!`);\n  },\n});\n

\n\n

Serves the src/index.html file just right:

\n❯ xh --headers http://localhost:3000/index.html\nHTTP/1.1 200 OK\nContent-Length: 889\nContent-Type: text/html;charset=utf-8\n

\n\n

Serving an HTML file with Node + Fastify

First, install the plugin:

❯ npm i @fastify/static

\n\n

And make this change:

\n+import path from "node:path";\n+\n import fastify from "fastify";\n+import fastifyStatic from "@fastify/static";\n\n const PORT = parseInt(process.env.PORT || "3000");\n\n const server = fastify();\n\n+server.register(fastifyStatic, {\n+  root: path.resolve("src"),\n+});\n+\n server.get("/", async () => {\n   return "Home page!";\n });\n server.get("/json", (request, reply) => {\n   reply.send({ hello: "world" });\n });\n\n+server.get("/index.html", (request, reply) => {\n+  reply.sendFile("index.html");\n+});\n+\n server.listen({ port: PORT }, (err, address) => {\n   if (err) {\n     console.error(err);\n

\n\n

And it works great:

\n❯ xh --headers http://localhost:3000/index.html\nHTTP/1.1 200 OK\nAccept-Ranges: bytes\nCache-Control: public, max-age=0\nConnection: keep-alive\nContent-Length: 889\nContent-Type: text/html; charset=UTF-8\nDate: Sat, 09 Sep 2023 03:04:15 GMT\nEtag: W/"379-18a77e4e346"\nKeep-Alive: timeout=72\nLast-Modified: Sat, 09 Sep 2023 03:03:23 GMT\n

\n\n

Quick benchmark of serving the HTML file

Bun

\n❯ hey -n 10000 -c 100 http://localhost:3000/index.html\n\nSummary:\n  Total:    0.6408 secs\n  Slowest:  0.0160 secs\n  Fastest:  0.0001 secs\n  Average:  0.0063 secs\n  Requests/sec: 15605.9735\n\n  Total data:   8890000 bytes\n  Size/request: 889 bytes\n

\n\n

Node + Fastify

\n❯ hey -n 10000 -c 100 http://localhost:3000/index.html\n\nSummary:\n  Total:    1.5473 secs\n  Slowest:  0.0272 secs\n  Fastest:  0.0078 secs\n  Average:  0.0154 secs\n  Requests/sec: 6462.9597\n\n  Total data:   8890000 bytes\n  Size/request: 889 bytes\n

\n\n

Again, a 2x performance win for Bun.

Conclusion

There isn't much to conclude here. Just an intro to the beauty of how quick Bun is, both in terms of developer experience and raw performance.
\nWhat I admire about Bun being such a convenient bundle is that Python'esque feeling of simplicity and minimalism. (For example python3.11 -m http.server -d src 3000 will make http://localhost:3000/index.html work)

The basic boilerplate of Node with Fastify + TypeScript + nodemon + ts-node is a great one if you're not ready to make the leap to Bun. I would certainly use it again. Fastify might not be the fastest server in the Node ecosystem, but it's good enough.

What's not shown in this little intro blog post, and is perhaps a silly thing to focus on, is the speed with which you type bun --hot src/index.ts and the server is ready to go. It's as far as human perception goes instant. The npm run dev on the other hand has this ~3 second \"lag\". Not everyone cares about that, but I do. It's more of an ethos. It's that wonderful feeling that you don't pause your thinking.

$\"npm$

It's hard to see when I press the Enter key but compare that to Bun:

$\"bun$

UPDATE (Sep 11, 2023)

I found this: github.com/SaltyAom/bun-http-framework-benchmark
\nIt's a much better benchmark than mine here. Mind you, as long as you're not using something horribly slow, and you're not doing any I/O the HTTP framework performances don't matter much.

","comments",4,[28,29,13],"Node","JavaScript","split","nextPage","previousPage",1,"page",2,"actionData","errors"]

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Hello-world server in Bun vs Fastify

September 9, 2023