我要做什么？
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，通知用户，一旦用户说“升级”，serviceWorker就会调用skipWaiting()
到目前为止我做了什么？
我正在关注一篇不错的文章https://redfin.engineering/how-to-fix-the-refresh-button-when-using-service-workers-a8e27af6df68，以实现
为了消除复杂性，我仅测试serviceWorkers之间的消息发送，以了解skipWaiting的工作方式。我正在使用create-react-app (v"react": "^16.5.2",)附带的workbox捆绑为插件。
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，当一个新的serviceWorker是installed时，我将以{p>
postMessage并且我希望消息可以通过
函数处理console.log('>> New content is available; please refresh.');
navigator.serviceWorker.controller.postMessage('skipWaiting');
然后，我部署我的更改，以便此 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}`);
});
准备就绪。
然后，我对应用程序（serviceWorker进行了更改，现在部署时，我看到记录了多条消息，但没有显示index.html
skipWaiting我在这里做什么错了？
答案 0 :(得分：0)
有些错误的地方
navigator.serviceWorker.controller.postMessage('skipWaiting'); 这是从window向worker发送一条消息，但是您正在等待window上的消息
postMessage()会将消息发送给该工作人员。message事件处理程序中运行代码，也不会这样做 if (messageEvent.data === 'skipWaiting') {
console.log('skipWaiting');
return navigator.serviceWorker.getRegistration(swUrl)
.then(registration => registration.skipWaiting());
}
没有registration.skipWaiting()方法。我们在skipWaiting代码内调用service-worker.js
在您的情况下，您将在工作程序代码中添加message的事件监听器，并在其中拦截“跳过等待”消息
self.addEventListener('message', (event) => {
if (event.data == 'skipWaiting') self.skipWaiting();
});
向现在安装的工作人员发送消息，以跳过等待并接管
console.log('>> New content is available; please refresh.');
installingWorker.postMessage('skipWaiting');