feat: Setup precache with service-worker

package.json

@@ -33,11 +33,15 @@
     "eslint-plugin-vue": "^5.2.2",
     "parcel-bundler": "^1.12.0",
     "parcel-plugin-static-files-copy": "^2.0.0",
+    "parcel-plugin-sw-precache": "^1.0.4",
     "vue-hot-reload-api": "^2.3.3",
     "vue-template-compiler": "^2.6.8"
   },
   "staticFiles": {
     "staticPath": "public",
     "watcherGlob": "**"
+  },
+  "sw-precache": {
+    "maximumFileSizeToCacheInBytes": 10485760
   }
 }

src/main.js

@@ -2,9 +2,13 @@ import Vue from 'vue'
 import App from '/App.vue'
 import store from '/store'
 
+import registerServiceWorker from '/register-service-worker.js'
+
 Vue.config.productionTip = false
 
 new Vue({
   store,
   render: h => h(App)
 }).$mount('#app')
+
+registerServiceWorker()

src/register-service-worker.js

@@ -0,0 +1,100 @@
+
+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('/', 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 = `/service-worker.js`
+
+      if (isLocalhost) {
+        // This is running on localhost. Lets check if a service worker still exists or not.
+        checkValidServiceWorker(swUrl)
+
+        // Add some additional logging to localhost, pointing developers to the
+        // service worker/PWA documentation.
+        navigator.serviceWorker.ready.then(() => {
+          console.log(
+            'This web app is being served cache-first by a service ' +
+              'worker. To learn more, visit https://goo.gl/SC7cgQ'
+          )
+        })
+      } else {
+        // Is not local host. Just register service worker
+        registerValidSW(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.'
+      )
+    })
+}