Web Workers

• main thread : where browser runs script, processes user events, painting, garbage collection
• worker threads: where a web worker runs code in parallel to thread that spawned it
  • data is only copied [thread safe]
  • have own event loops
  • no DOM access, no access to window, not all web APIs are available
  • uses self to access worker scope

Shared Workers

• a Worker can only be accessed from script that created it,
• a SharedWorker can be accessed by any script that comes from the same domain (different windows, iframes, workers.)
• uses an explicit port object to communicate

Service Workers

• act as proxy servers between webapp, browser and network (when available)
• used to create offline webapps, executing code based on if network is available.
• allow access to push notifications and background sync APIs