Web Workers enable multi-threaded JavaScript. Here's how to use them for heavy computation without blocking the UI.
Basic Web Worker
TypeScript Web Worker
Transferable Objects
Worker Pool
Shared Worker
Comlink for Easy Workers
OffscreenCanvas
Best Practices
When to Use:
✓ Heavy computations (sorting, parsing)
✓ Image/video processing
✓ Data transformation
✓ Complex calculations
When NOT to Use:
✗ Simple operations
✗ DOM manipulation (not allowed)
✗ Small data sets
✗ Frequent small messages
Performance:
✓ Use transferable objects
✓ Minimize message passing
✓ Pool workers for many tasks
✓ Terminate unused workers
Communication:
✓ Structure messages clearly
✓ Handle errors properly
✓ Consider using Comlink
✓ Batch small messages
Conclusion
Web Workers enable parallel processing in JavaScript without blocking the main thread. Use them for CPU-intensive tasks, leverage transferable objects for large data, and consider worker pools for concurrent processing. Libraries like Comlink simplify the communication API significantly.