linting, package and serviceWorker

.eslintrc

@@ -0,0 +1,16 @@
+{
+  "extends": ["airbnb", "prettier"],
+  "rules": {
+    "react/jsx-filename-extension": [{
+      "extensions": [".js", ".jsx"]
+    }],
+    "linebreak-style": "off",
+    "prettier/prettier": ["error"],
+    "react/prop-types": false,
+    "import/no-cycle": false
+  },
+  "plugins": ["prettier"],
+  "env": {
+    "browser": true
+  }
+}

.prettierrc

@@ -2,5 +2,6 @@
   "semi": true,
   "singleQuote": true,
   "jsxSingleQuote": true,
-  "trailingComma": "es5"
+  "trailingComma": "es5",
+  "printWidth": 100
 }

package.json

@@ -3,23 +3,21 @@
   "version": "0.1.0",
   "private": true,
   "dependencies": {
-    "@types/react-router-dom": "^4.3.1",
     "react": "^16.8.1",
     "react-dom": "^16.8.1",
     "react-router-dom": "^4.3.1"
   },
   "devDependencies": {
-    "@types/node": "10.12.21",
+    "eslint": "^5.12.0",
-    "@types/react": "16.8.2",
+    "eslint-config-airbnb": "^17.1.0",
-    "@types/react-dom": "16.8.0",
+    "eslint-config-prettier": "^4.1.0",
+    "eslint-plugin-import": "^2.17.2",
+    "eslint-plugin-jsx-a11y": "^6.2.1",
+    "eslint-plugin-prettier": "^3.0.1",
+    "eslint-plugin-react": "^7.12.4",
     "node-sass": "^4.11.0",
-    "prettier": "^1.16.4",
+    "prettier": "^1.17.0",
-    "react-scripts": "2.1.3",
+    "react-scripts": "^2.1.8"
-    "tslint": "^5.12.1",
-    "tslint-config-prettier": "^1.18.0",
-    "tslint-config-standard": "^8.0.1",
-    "tslint-react": "^3.6.0",
-    "typescript": "3.3.1"
   },
   "scripts": {
     "start": "react-scripts start",

serviceWorker.js

@@ -0,0 +1,135 @@
+// This optional code is used to register a service worker.
+// register() is not called by default.
+
+// 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 subsequent visits to a page, after all the
+// existing tabs open on the page have been closed, since previously cached
+// resources are updated in the background.
+
+// To learn more about the benefits of this model and instructions on how to
+// opt-in, read https://bit.ly/CRA-PWA
+
+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}$/
+    )
+);
+
+export function register(config) {
+  if (process.env.NODE_ENV === 'production' && 'serviceWorker' in navigator) {
+    // The URL constructor is available in all browsers that support SW.
+    const publicUrl = new URL(process.env.PUBLIC_URL, window.location.href);
+    if (publicUrl.origin !== window.location.origin) {
+      // Our service worker won't work if PUBLIC_URL is on a different origin
+      // from what our page is served on. This might happen if a CDN is used to
+      // serve assets; see https://github.com/facebook/create-react-app/issues/2374
+      return;
+    }
+
+    window.addEventListener('load', () => {
+      const swUrl = `${process.env.PUBLIC_URL}/service-worker.js`;
+
+      if (isLocalhost) {
+        // This is running on localhost. Let's check if a service worker still exists or not.
+        checkValidServiceWorker(swUrl, config);
+
+        // 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://bit.ly/CRA-PWA'
+          );
+        });
+      } else {
+        // Is not localhost. Just register service worker
+        registerValidSW(swUrl, config);
+      }
+    });
+  }
+}
+
+function registerValidSW(swUrl, config) {
+  navigator.serviceWorker
+    .register(swUrl)
+    .then(registration => {
+      registration.onupdatefound = () => {
+        const installingWorker = registration.installing;
+        if (installingWorker == null) {
+          return;
+        }
+        installingWorker.onstatechange = () => {
+          if (installingWorker.state === 'installed') {
+            if (navigator.serviceWorker.controller) {
+              // At this point, the updated precached content has been fetched,
+              // but the previous service worker will still serve the older
+              // content until all client tabs are closed.
+              console.log(
+                'New content is available and will be used when all ' +
+                  'tabs for this page are closed. See https://bit.ly/CRA-PWA.'
+              );
+
+              // Execute callback
+              if (config && config.onUpdate) {
+                config.onUpdate(registration);
+              }
+            } 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.');
+
+              // Execute callback
+              if (config && config.onSuccess) {
+                config.onSuccess(registration);
+              }
+            }
+          }
+        };
+      };
+    })
+    .catch(error => {
+      console.error('Error during service worker registration:', error);
+    });
+}
+
+function checkValidServiceWorker(swUrl, config) {
+  // 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.
+      const contentType = response.headers.get('content-type');
+      if (
+        response.status === 404 ||
+        (contentType != null && contentType.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, config);
+      }
+    })
+    .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();
+    });
+  }
+}