Javascript 活动serviceWorker未向正在等待的serviceWorker发送消息

我想做什么？

我正在创建一个渐进式web应用程序（PWA），为了正确发送升级应用程序，我正在执行一个步骤，在该步骤中，用户会收到通知，一旦用户说“升级”，服务工作者就会调用

skipWaiting（）

到目前为止我做了什么？
我正在跟进一篇好文章来实现这一点

为了消除复杂性，我只测试

serviceworks

之间的消息发送，以了解

skipWaiting

的工作原理。我正在使用

createreact应用程序（v“react”：“^16.5.2”，）

，它作为插件捆绑在

workbox

中

我当前的

registerServiceWorker.js

看起来像

// In production, we register a service worker to serve assets from local cache.

// This lets the app load faster on subsequent visits in production, and gives
// it offline capabilities. However, it also means that developers (and users)
// will only see deployed updates on the "N+1" visit to a page, since previously
// cached resources are updated in the background.

// To learn more about the benefits of this model, read 
// This link also includes instructions on opting out of this behavior.

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);
      }
    });

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

      if (messageEvent.data === 'skipWaiting') {
        console.log('skipWaiting');
        return navigator.serviceWorker.getRegistration(swUrl)
          .then(registration => registration.skipWaiting());
      }

      console.log(`message=${messageEvent.data}`);
    });

    let refreshingPage;
    navigator.serviceWorker.addEventListener('controllerchange', () => {
      console.log('refreshing page now');
      if (refreshingPage) return;
      refreshingPage = true;
      window.location.reload();
    });
  }
}

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.');
              navigator.serviceWorker.controller.postMessage('skipWaiting');
            } 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();
    });
  }
}

如您所见，当安装了一个新的serviceWorker时，我会以

console.log('>> New content is available; please refresh.');
navigator.serviceWorker.controller.postMessage('skipWaiting');

我希望这个消息能用这个函数来处理

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

      if (messageEvent.data === 'skipWaiting') {
        console.log('skipWaiting');
        return navigator.serviceWorker.getRegistration(swUrl)
          .then(registration => registration.skipWaiting());
      }

      console.log(`message=${messageEvent.data}`);
    });

然后，我部署我的更改，以便此

serviceWorker

就绪。 然后，我对我的应用程序进行了更改（

index.html

），现在当我部署时，我看到有多条消息被记录，但没有一条消息是使用

skipWaiting

message=
registerServiceWorker.js:53 message=!_{"h":"I0_1548194465894"}
registerServiceWorker.js:53 message=!_{"s":"/I0_1548194465894::_g_rpcReady","f":"I0_1548194465894","r":"I0_1548194465894","t":"32296067","c":1,"a":[null],"g":false}
registerServiceWorker.js:53 message=!_{"s":"__cb","f":"I0_1548194465894","r":"I0_1548194465894","t":"32296067","c":null,"a":[1,[null]],"g":false}
registerServiceWorker.js:53 message=!_{"s":"__cb","f":"I0_1548194465894","r":"I0_1548194465894","t":"32296067","c":null,"a":[2,[null]],"g":false}
registerServiceWorker.js:53 message=!_{"s":"/I0_1548194465894::_g_restyleMe","f":"I0_1548194465894","r":"I0_1548194465894","t":"32296067","c":2,"a":[{"setHideOnLeave":false}],"g":false}
registerServiceWorker.js:53 message=!_{"s":"__cb","f":"I0_1548194465894","r":"I0_1548194465894","t":"32296067","c":null,"a":[4,[null]],"g":false}
registerServiceWorker.js:53 message=!_{"s":"/I0_1548194465894::authEvent","f":"I0_1548194465894","r":"I0_1548194465894","t":"32296067","c":3,"a":[{"type":"authEvent","authEvent":{"type":"unknown","eventId":null,"urlResponse":null,"sessionId":null,"postBody":null,"tenantId":null,"error":{"code":"auth/no-auth-event","message":"An internal error has occurred."}}}],"g":false}
registerServiceWorker.js:53 message=!_{"s":"__cb","f":"I0_1548194465894","r":"I0_1548194465894","t":"32296067","c":null,"a":[3,[true]],"g":false}

---

我做错了什么？

有几件事做错了

navigator.serviceworner.controller.postMessage（'skipWaiting'）

这是从

窗口

向

工作者

发送消息，但您正在等待

窗口上的消息

• 控制器->不是工作实例

  postMessage（）

  将向该工作人员发送消息
• 但是，您不想向该工作人员发布消息-它是您当前的活动工作人员，而您希望通知尚未接管的新安装工作人员

即使您设法在

消息

事件处理程序中运行代码，它也不会运行

if（messageEvent.data=='skipWaiting'）{
控制台日志（“skipWaiting”）；
返回navigator.serviceWorker.getRegistration（swUrl）
.then（registration=>registration.skipWaiting（））；
}

没有注册.skipWaiting（）方法。我们在

service worker.js

code中调用

skipWaiting

在您的情况下，您需要在工作代码中为

message

添加一个事件侦听器，并在那里拦截“Skip Waiting”消息

工作代码

self.addEventListener（'message'，（event）=>{
if（event.data=='skipWaiting'）self.skipWaiting（）；
});

窗口代码（仅限更改） 向现在已安装的工作人员发送消息以跳过等待并接管

console.log（“>>新内容可用；请刷新”）；
安装worker.postMessage（'skipWaiting'）；

这段代码看起来很混乱。您在这里只展示了一个脚本，

registerServiceWorker.js

，它在页面中运行，但服务工作者至少需要两个脚本，一个在页面中运行，一个在服务工作者中运行。我建议通过谷歌的Udacity课程来学习这些材料。