Web Workers in Bun
From the Bun cheat sheet · Workers & Concurrency · verified Jul 2026
Web Workers
Run CPU-intensive tasks in parallel threads
typescript
// main.ts
const worker = new Worker("./worker.ts");
worker.postMessage({ data: [1, 2, 3] });
worker.onmessage = (e) => {
console.log("Result:", e.data);
};
// worker.ts
self.onmessage = (e) => {
const result = e.data.data.map((n) => n * 2);
self.postMessage(result);
};💡 Bun Workers support TypeScript directly — no build step needed for worker files
⚡ Use navigator.hardwareConcurrency to create an optimal number of workers for the CPU
📌 Workers run in separate threads with isolated memory — communicate via postMessage
🟢 Use workers for CPU-intensive tasks (parsing, compression, crypto) to keep the main thread responsive
workersconcurrencythreadsparallel
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