A script to reproduce streaming response bug in bun that's affecting express.js.

bun-express-streaming-response-bug.sh

#!/bin/bash

TIMESTAMP=$(date +%s)
mkdir "bun-express-streaming-response-bug-$TIMESTAMP/"
cd "bun-express-streaming-response-bug-$TIMESTAMP/"

cat <<EOT > package.json
{ "dependencies": { "express": "^4.18.2" }, "type": "module" }
EOT

cat <<EOT > index.js
import express from "express";

const port = process.argv[2];
const app = express();

async function sleep(ms) {
  return new Promise((resolve) => setTimeout(resolve, ms));
}

app.get("/", async (req, res) => {
  res.set({ "transfer-encoding": "chunked" });
  res.write("1\n");
  await sleep(300);
  res.write("2\n");
  await sleep(300);
  res.write("3\n");
  await sleep(300);
  res.write("4\n");
  await sleep(300);
  res.write("5\n");
  await sleep(300);
  res.end();
});

app.listen(port, () => {
  console.log("Example app listening on port " + port);
});
EOT

bun install
bun run index.js 3001 & node index.js 3002