Web workers allow JavaScript to run in background threads to optimize performance. A worker runs in a separate global context and can communicate with the main thread via messaging. A shared worker can serve multiple browsing contexts and uses ports to send and receive messages between contexts. Workers parallelize work to speed up tasks while shared workers facilitate sharing state across contexts by using a single worker instance.

1. Web Workers
Ran Wahle

2. Agenda
● What are web workers?
● Worker
● SharedWorker

3. What are web workers?
● A javascript object
● Should run in another thread
● Have different scope
● Can interact with the main js thread

4. Initialize and working with WebWorker
● Feature detect
● Spawn by calling the Worker() constructor
● Handle messaging

5. Messaging -code sample

6. Shared Workers

7. What is a shared worker?
One worker can serve many browsing contexts
Worker sends and receives messages through a port

8. SharedWorker Internals
Handle the “connect” event of the shared worker

9. Worker Vs. SharedWorker
WebWorker SharedWorker
Different scope Different scope
One / Many per context One / Many per many contextes
worker.postMessage worker.port.postMessage
self.onmessage = message => {...} Use onconnect

10. Summary
Workers can both makes our work faster, by parallelize our
work, and with SharedWorkers we may easily share one
worker instance between many view context, and easily
share state by that.

11. Demo code
https://github.com/ranwahle/jsil-webworkerDemo

12. Thank you
@ranwahle
ran.wahle@gmail.com
ranw@tikalk.com