Service Worker
A Service Worker is a script that runs in the browser background independently of the main web page thread, forming part of the Web API. It acts as a proxy layer between the browser and the network, intercepting and handling network requests and managing cached resources to enable offline access, page performance optimization, push notifications, and background data synchronization. Service Workers operate on an event-driven model, require an HTTPS environment, and are a core technology for building Progressive Web Apps (PWAs).
Core Facts
PWA is a form of web application that Google heavily promoted around 2015, relying on three key technologies: Service Worker, Web App Manifest, and HTTPS.
Manifest V3 replaces the previously long-running Background Page with a Service Worker
The three core technical components of a PWA are Service Worker, Web App Manifest, and mandatory HTTPS connections.
Timeline (last 90 days)
After the Service Worker caches static resources, the app can be used fully offline, but the core data of the bookkeeping app is in localStorage, the Service Worker does not cache the data itself, and because there is no server, transactions entered offline will not automatically sync after the network is restored.
Through the Web App Manifest and Service Worker, the app can be "installed" to the Android or iOS home screen, running in a standalone window with the browser address bar hidden, delivering an experience close to a native app.
Service Worker requires the page to run over HTTPS or localhost, and it is fully asynchronous and cannot directly access the DOM.
Data in localStorage and IndexedDB is bound to a specific domain and browser instance, and clearing browser data or changing browsers or devices will make the data inaccessible; they do not participate in the Service Worker caching mechanism and cannot automatically sync to the server.
A Service Worker is a script running in the background that can intercept network requests and cache resources, thereby enabling offline access and fast loading; its lifecycle includes events such as install, activate, and fetch.
The Fetch API is a new-generation network request interface standardized around 2015 alongside Service Worker, designed based on Promises.
GrassToucher implements a Service Worker (sw.js) with a cache fallback strategy via cache.put(), allowing the app to remain responsive and functional when out of network coverage.
Go Outside uses the Service Worker's Cache Storage API to persist weights and the application itself locally, enabling full functionality including model inference even offline after the first successful load.
Some advanced projects introduce Service Workers to simulate file systems, or use WebAssembly to run real Unix toolchains.
Offline availability is typically implemented using PWA technology, where a Service Worker caches key resources locally during the first visit so that subsequent visits can load from the cache bypassing the network.
13 more timeline events
All Facts (20)
PWA is a form of web application that Google heavily promoted around 2015, relying on three key technologies: Service Worker, Web App Manifest, and HTTPS.
80%VerifiedManifest V3 replaces the previously long-running Background Page with a Service Worker
75%VerifiedThe three core technical components of a PWA are Service Worker, Web App Manifest, and mandatory HTTPS connections.
70%VerifiedA Service Worker is essentially a script thread running independently in the browser background, acting as a proxy layer between the web application and the network and capable of intercepting network requests.
65%UnverifiedService Worker是运行在浏览器主线程之外的独立JavaScript工作线程，具有安装、激活和运行三个生命周期阶段
95%UnverifiedService Worker需要HTTPS环境才能注册，且不支持IE浏览器
95%UnverifiedChrome的Service Worker在空闲约30秒后会被浏览器主动终止以节省内存和CPU资源
80%UnverifiedPWAs implement offline caching and background sync via Service Workers, and push notifications via the Web Push API.
60%UnverifiedApple did not support Service Workers in Safari until 2018, and only conditionally supported Web Push notifications starting with iOS 16.4.
60%UnverifiedAfter the Service Worker caches static resources, the app can be used fully offline, but the core data of the bookkeeping app is in localStorage, the Service Worker does not cache the data itself, and because there is no server, transactions entered offline will not automatically sync after the network is restored.
50%UnverifiedThrough the Web App Manifest and Service Worker, the app can be "installed" to the Android or iOS home screen, running in a standalone window with the browser address bar hidden, delivering an experience close to a native app.
50%UnverifiedService Worker requires the page to run over HTTPS or localhost, and it is fully asynchronous and cannot directly access the DOM.
50%UnverifiedData in localStorage and IndexedDB is bound to a specific domain and browser instance, and clearing browser data or changing browsers or devices will make the data inaccessible; they do not participate in the Service Worker caching mechanism and cannot automatically sync to the server.
50%UnverifiedA Service Worker is a script running in the background that can intercept network requests and cache resources, thereby enabling offline access and fast loading; its lifecycle includes events such as install, activate, and fetch.
50%UnverifiedThe Fetch API is a new-generation network request interface standardized around 2015 alongside Service Worker, designed based on Promises.
50%UnverifiedGrassToucher implements a Service Worker (sw.js) with a cache fallback strategy via cache.put(), allowing the app to remain responsive and functional when out of network coverage.
50%UnverifiedGo Outside uses the Service Worker's Cache Storage API to persist weights and the application itself locally, enabling full functionality including model inference even offline after the first successful load.
50%UnverifiedSome advanced projects introduce Service Workers to simulate file systems, or use WebAssembly to run real Unix toolchains.
50%UnverifiedOffline availability is typically implemented using PWA technology, where a Service Worker caches key resources locally during the first visit so that subsequent visits can load from the cache bypassing the network.
50%UnverifiedService Workers can download new version resources in the background and, after the download is complete, notify the main page via a message, letting the user actively decide when to activate the new version.
50%