[Javascript](Web 기술) serviceWorker , PushManager , Web Worker

* PushManager ( in window )
https://developer.mozilla.org/ko/docs/Web/API/PushManager
 푸시 알림 송수신 기능
getSubscription()
hasPermission() 
permissionState()
register() 
registrations() 
subscribe() 
unregister()


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* navigator
https://www.w3schools.com/jsref/obj_navigator.asp
브라우저에 관한 정보를 제공해주는 객체
productSub: "20030107"
vendor: "Google Inc."
cookieEnabled: true
appCodeName: "Mozilla"
appName: "Netscape"
appVersion: "5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.16 Safari/537.36"
platform: "Win32"
product: "Gecko"
userAgent: "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.16 Safari/537.36"
language: "ko"
languages: (2) ["ko", "en-US"]
onLine: true
doNotTrack: "1"
geolocation: Geolocation {}
userActivation: UserActivation {hasBeenActive: false, isActive: false}
serviceWorker: ServiceWorkerContainer {ready: Promise, controller: ServiceWorker, oncontrollerchange: null, onmessage: null}
storage: StorageManager {}
presentation: Presentation {receiver: null, defaultRequest: null}


//====================
* serviceWorker (in navigator)
https://developers.google.com/web/fundamentals/primers/service-workers/?hl=ko
- 브라우저가 백그라운드에서 실행하는 스크립트
- HTTPS 필요
캐시(cache)와 상호작용 , 푸시 알림(Push Notification) 보내기, 백그라운드 동기화(Background Sync)


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* Web Worker ( Worker in window )
http://blog.302chanwoo.com/2016/08/webworker/
- Background Thread에서 스크립트를 실행하는 방법

웹 워커 활용
– 매우 복잡한 수학적 계산 작업
– 원격지에 있는 리소스에 대한 액세스 작업(또는 로컬 스토로지를 액세스 하는 경우)
– 백그라운드에서 오랜시간 작업해야 하는 경우
– UI 쓰레드에 방해 없이 지속적으로 수행해야 하는 작업 등