使用 Service-Worker React 的离线页面

Question

我是服务人员的新手！我在本地主机中有一个反应站点运行ning 并且即将部署。我遵循指定的代码 here.

const isLocalhost = Boolean(
window.location.hostname === 'localhost' ||
    // [::1] is the IPv6 localhost address.
    window.location.hostname === '[::1]' ||
    // 127.0.0.1/8 is considered localhost for IPv4.
    window.location.hostname.match(
      /^127(?:\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3}$/
    )
)

export default function register () {
  if (process.env.NODE_ENV === 'production' && 'serviceWorker' in navigator) {
    // The URL constructor is available in all browsers that support SW.
    const publicUrl = new URL(process.env.PUBLIC_URL, window.location)
    if (publicUrl.origin !== window.location.origin) {
      // Our service worker won't work if PUBLIC_URL is on a different origin
      // from what our page is served on. This might happen if a CDN is used to
      // serve assets; see https://github.com/facebookincubator/create-react-app/issues/2374
      return
    }

    window.addEventListener('load', () => {
      const swUrl = `${process.env.PUBLIC_URL}/service-worker.js`

      if (!isLocalhost) {
        // Is not local host. Just register service worker
        registerValidSW(swUrl)
      } else {
        // This is running on localhost. Lets check if a service worker still exists or not.
        checkValidServiceWorker(swUrl)
      }
    })
  }
}

function registerValidSW (swUrl) {
  navigator.serviceWorker
    .register(swUrl)
    .then(registration => {
      registration.onupdatefound = () => {
        const installingWorker = registration.installing
        installingWorker.onstatechange = () => {
          if (installingWorker.state === 'installed') {
            if (navigator.serviceWorker.controller) {
              // At this point, the old content will have been purged and
              // the fresh content will have been added to the cache.
              // It's the perfect time to display a "New content is
              // available; please refresh." message in your web app.
              console.log('New content is available; please refresh.')
            } else {
              // At this point, everything has been precached.
              // It's the perfect time to display a
              // "Content is cached for offline use." message.
              console.log('Content is cached for offline use.')
            }
          }
        }
      }
    })
    .catch(error => {
      console.error('Error during service worker registration:', error)
    })
}

function checkValidServiceWorker (swUrl) {
  // Check if the service worker can be found. If it can't reload the page.
  fetch(swUrl)
    .then(response => {
      // Ensure service worker exists, and that we really are getting a JS file.
      if (
        response.status === 404 ||
        response.headers.get('content-type').indexOf('javascript') === -1
      ) {
        // No service worker found. Probably a different app. Reload the page.
        navigator.serviceWorker.ready.then(registration => {
          registration.unregister().then(() => {
            window.location.reload()
          })
        })
      } else {
        // Service worker found. Proceed as normal.
        registerValidSW(swUrl)
      }
    })
    .catch(() => {
      console.log(
        'No internet connection found. App is running in offline mode.'
      )
    })
}

export function unregister () {
  if ('serviceWorker' in navigator) {
    navigator.serviceWorker.ready.then(registration => {
      registration.unregister()
    })
  }
}

这只适用于生产，但我希望离线站点在 localhost 中运行并且只缓存基本路由，即 /。我不想缓存任何其他页面。
任何帮助是极大的赞赏！
谢谢！

Answer 1

以下是您可以执行的操作。

//this is your settings component
export default function Settings(props) {
  const [offline, setOffline] = useState(false);
  useEffect(() => {
    if(!navigator.onLine) setOffline(true);
  }, []);
  return (
    <>
    {offline && (
       <div>You are offline please connect to the internet</div>
       <button onClick={() => window.location.reload(true)}>Refresh</button>
    )}
    {!offline && (
      <div>This is my actual settings page</div>
    )}
    </>
  );
}

好了，您可以根据用户离线情况有条件地呈现您的设置。或者您也可以尝试在获取失败（用户离线）时提醒用户。如下所示：

export default function Settings(props) {
  const handleAPICall = () => {
    fetch(YOUR_API_ENDPOINT).then(res => res.json()).then(data => useData(data)).catch(err => {
      setOffline(true);
    });
  }
  return (
    <>
     {offline && (
       <Alert timeout={'3s'}>You are offline please connect to the internet</Alert>
     )}
     <div>
        <p>This is my actual settings page</p>
        <button onClick={handleAPICall}>Fetch data</button>
     </div>
    </>
  );
    </>
  );
}

我希望您能找到适合您的这些方法之一。看，首先让您的 Web 应用程序的一部分脱机从来都不是解决问题的正确方法。有时很难提出正确的问题，因为您自己并不知道自己想要什么。但是我们还要继续磨。

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