Service worker - jellyfish-tom/TIL GitHub Wiki

[SOURCES]

• https://alligator.io/js/service-workers/

Service Workers are browser feature that provide event-driven scripts that run independently of web pages. They are at the core of Progressive Web Apps (PWAs)

Greatest Service Workers advantages are:

• offline access of website content
• easy mobile devices access
• non UI blocking operation

Service Workers characteristics:

• needs to be served through HTTPS
• service workers can intercept network requests
• can serve cached (cache happen during interception) resources browser is offline and the network is unavailable
• runs on a separate thread
• can’t access many objects available (because of being single threaded) in the main JavaScript thread, including access to the DOM and several APIs like XHR, or Cookies
• service workers operation can’t ever block the UI thread, because it’s completely separate
• during first webpage visit service worker can only be instaled. Only during following visits it can serve cached recources, intercept network requests etc.