將eventlisteners放在serviceworker上的位置

Question

基本上我正在嘗試完成以在檢測到新的serviceworker版本時顯示對話框，然后讓用戶決定重新加載以獲取它。 為了實現這一點，我們需要在重新加載窗口之前主動設置skipWaiting 。

這是我的行動：

  onClickHandler = () => {
    console.log('on click', 'posting skipWaiting');
    navigator.serviceWorker.controller.postMessage('skipWaiting');
  };

這是我嘗試創建eventListener：

navigator.serviceWorker
    .register(swUrl)
    .then(registration => {
      registration.onupdatefound = () => {
        const installingWorker = registration.installing;
        if (installingWorker == null) {
          return;
        }
        installingWorker.onstatechange = () => {
          console.log('worker state', installingWorker.state);
          if (installingWorker.state === 'installed') {
            if (navigator.serviceWorker.controller) {
              console.log(
                'New content is available and will be used when all ' +
                  'tabs for this page are closed.'
              );

              navigator.serviceWorker.addEventListener('message', event => {
                console.log('skip waiting');
                if (event.data === 'skipWaiting') {
                  self.skipWaiting();
                }
              });
            }
          }
        };
      };
    })
    .catch(error => {
      console.error('Error during service worker registration:', error);
    });

問題是navigator.serviceWorker.addEventListener('message', event =>沒有被觸發。我是否聲明監聽器錯了？

Answer 1

你很親密 在您安裝的區塊中，您可以進行檢查

navigator.serviceWorker.controller

如果存在，則表示舊內容已被清除，新內容將被添加到緩存中。 它是顯示消息或強制刷新的最佳時機。

  navigator.serviceWorker.register('service-worker.js').then(function (registration) {

                    $log.debug('The service worker has been registered ', registration);

                    if(navigator.online) {
                        toastr.warning('Offline Mode', 'Application Status');
                    }

                    // updatefound is fired if service-worker.js changes.
                    registration.onupdatefound = function () {
                        // The updatefound event implies that reg.installing is set; see
                        // https://slightlyoff.github.io/ServiceWorker/spec/service_worker/index.html#service-worker-container-updatefound-event
                        var installingWorker = registration.installing;

                        installingWorker.onstatechange = function () {
                            switch (installingWorker.state) {
                                case '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 the page's interface.
                                        toastr.info('Application has been updated, please refresh this page for the most recent version');

                                        window.location.reload();

                                        });
                                        caches.delete('scope-dynamic').then(function () {
                                            $log.debug('Killed the dynamic cache!');
                                        })
                                        $log.debug('New or updated content is available.');
                                    } else {
                                        // At this point, everything has been precached.
                                        // It's the perfect time to display a "Content is cached for offline use." message.
                                        toastr.success('Content is cached for offline use.', 'Application Status');
                                        $log.debug('Content is now available offline!');
                                    }
                                    break;

                                case 'redundant':
                                    $log.error('The installing service worker became redundant.');
                                    break;

                            }
                        };
                    };
                }).catch(function (e) {
                    $log.error('Error during service worker registration:', e);
                });

那里撒了一些棱角分明的東西，但這應該可以幫助你到達你想去的地方。

Answer 2

這里的問題是您提供的代碼僅定義了從客戶端向服務工作者接收和發送消息。

以下方法定義了要發送給控制器（活動）服務工作者的消息。

onClickHandler = () => {
    console.log('on click', 'posting skipWaiting');
    navigator.serviceWorker.controller.postMessage('skipWaiting');
};

下面的定義在ServiceWorker容器上添加了一個事件偵聽器，用於接收從服務工作者發送的任何消息。

navigator.serviceWorker.addEventListener('message', event => {
    console.log('skip waiting');
    if (event.data === 'skipWaiting') {
        self.skipWaiting();
    }
});

您現在需要從服務工作文件中定義事件處理程序以接收和發送消息。

在服務工作器文件中，要從客戶端接收消息：

self.addEventListener('message', function handler (event) {
   console.log('skip waiting');
   if (event.data === 'skipWaiting') {
      self.skipWaiting();
   }
});

要從serviceworker向您的客戶發送消息：

self.addEventListener('fetch', function(event) {
  self.clients.matchAll().then(all => all.map(client => client.postMessage('data from webworker')));
});

您還可以使用MessageChannel從serviceworker發回數據。 在您的客戶端上，您必須定義如下內容：

    navigator.serviceWorker
        .register(swUrl)
        .then(registration => {
            var messageChannel = new MessageChannel();
            // listener for messages from the ServiceWorker    
            messageChannel.port1.addEventListener('message', (event) => console.log(event.data)); 

            function sendMessage (message) {
                //send message to the active service worker
                navigator.serviceWorker.controller.postMessage(message, [messageChannel.port2]);
            }
      onClickHandler = () => {
          sendMessage('skipWaiting');
      };
   });

我發現下面的文章非常有幫助。

NicolásBevacqua提供的ServiceWorker，MessageChannel和postMessage