Service workers are your best friend!

The main API for PWA creation is Service Workers, they are the heart of this “new web”. With Service workers, we can send push notifications to the user or do background sync and show data even when the user is offline. They are not some science fiction, but a script that is quite easy to use.

In this talk, we will see overview what are service workers and when and how to use them.

Transcript

1. Service workers are your best friend! Antonio Perić-Mažar, Locastic 02.12.2018., #growITconf
2. Antonio Perić-Mažar CEO @ Locastic Co-Founder @ Blockada antonio@locastic.com @antonioperic
3. Locastic • We help clients create amazing web and mobile apps (since 2011) • mobile development • web development • UX/UI • Training and Consulting • Shift Conference, Symfony Croatia • www.locastic.com t: @locastic
5. [Mobile] User Experience on Web
6. MOBILE
7. UX
8. MOBILE.UX.
14. And trust me… you will never had enough cheese
15. “I don't care how many kick-ass Visio architecture diagrams you have; as far as the user is concerned, the UI is the application. I know UI US HARD, but you have to build an impressive UI if you want to be taken seriously. Give your UI the high priority it deserves.” Jeff Atwood, Coding Horror blog
17. Capebility Reach
18. “A Progressive Web App uses modern web capabilities to deliver an app-like user experience.”
19. “A Progressive Web App uses modern web capabilities to deliver an app-like user experience.”
20. PWA is: • Progressive - Works for every user, regardless of browser choice because it's built with progressive enhancement as a core tenet. • Responsive - Fits any form factor: desktop, mobile, tablet, or whatever is next. • Connectivity independent - Enhanced with service workers to work offline or on low-quality networks. • App-like - Feels like an app, because the app shell model separates the application functionality from application content . • Fresh - Always up-to-date thanks to the service worker update process.
21. PWA is: • Safe - Served via HTTPS to prevent snooping and to ensure content hasn't been tampered with. • Discoverable - Is identifiable as an "application" thanks to W3C manifest and service worker registration scope, allowing search engines to find it. • Re-engageable - Makes re-engagement easy through features like push notifications. • Installable - Allows users to add apps they find most useful to their home screen without the hassle of an app store. • Linkable - Easily share the application via URL, does not require complex installation.
23. Fast Integrated Reliable Engaging 4 things to focus on
24. Fast Integrated Reliable Engaging
25. Fast • No junky scrolling • No slow load performance • Measure and improve all the time • Bad connection (or no connection) is not excuse
26. 53% of users abandon sites that take longer than 3 seconds to load
27. https://cloudfour.com/thinks/ios-doesnt-support-progressive-web-apps-so-what/
29. App shell model • Reliable performance that is consistently fast • Native-like interactions • Economical use of data
30. Fast Integrated Reliable Engaging
31. Integrated • User should not reach browser to reach your app • They should be able to interact same as with any other app on their device • They expect to have all possibilities as other apps • Users should be able to start app from their home screen
32. https://www.mobigyaan.com/android-8-0-oreo-vs-ios-11-which-is-better
33. https://techcrunch.com/2017/08/25/majority-of-u-s-consumers-still-download-zero-apps-per-month-says-comscore/
34. https://techcrunch.com/2017/08/25/majority-of-u-s-consumers-still-download-zero-apps-per-month-says-comscore/
35. https://www.technology.org/2017/07/28/progressive-web-apps-vs-native-which-is-better-for-your-business/
36. 80% users intentionally moved apps to their home screen
37. Broken experience • Required user interaction • Where it will start? • Would it work offline? https://medium.com/@saigeleslie/how-to-create-a-progressive-web-app-with-react-in-5-mins-or-less-3aae3fe98902
38. Web manifest • Simple JSON file • Tell browsers about your app and how it should behave once app is ‘installed’ • Having manifest is required to show add to home screen pop-up • Works for desktop and mobile apps (chrome) • https://manifest-validator.appspot.com/ • https://app-manifest.firebaseapp.com/
39. { "background_color":"#ffffff", "display":"standalone", "icons":[ … ], "name":"Twitter", "short_name":"Twitter", "start_url":"/", "theme_color":"#ffffff", “scope":"/" } <link rel="manifest" href="/manifest.json"> You can add it now to 
 your app
41. https://ponyfoo.com/articles/progressive-app-serviceworker
42. 40% higher interaction rate from Home screen
43. Web Payment API!
44. 66% of purchases on mobile are on the web
45. 1/3 of purchases on Web are via mobile That means the UX 
 is BROKEN!
46. Checkout forms today: • Manual • Tedious • Slow • N-taps http://www.alyssatucker.com/improving-hollars-ios-checkout-process/
47. Autofill - step forward • Autocomplete attributes • 30% faster • Automatic • Simple • Slow • n-taps http://www.alyssatucker.com/improving-hollars-ios-checkout-process/
48. Web Payment API!
52. Web Payment API! • Automatic • Simple • Fast • 1-tap • Supportes payment gatway,
 or some applications payment 
 (Google Pay) https://paymentrequest.show/images/pr-woocommerce.gif
53. More APIs • Media Session • Media Capture API • Casting support • Web bluetooth • Web Share
54. More APIs • Media Session • Media Capture API • Casting support • Web bluetooth • Web Share
55. Remember users expect to be able to interact with your app in the same way that they do all of the other apps on their device
56. Fast Integrated Reliable Engaging
57. Reliable Reliability means, never showing the Downsaur
59. Reliable • The quality of a network connection can be affected by a number of factors such as: • Poor coverage of a provider. • Extreme weather conditions. • Power outages. • Users travelling into “dead zones” such as buildings that block their network connections. • Travelling on a train and going through a tunnel. • Internet connection is managed by a third party and time boxed when it will be active or inactive like in an airport or hotel. • Cultural practises that require limited or no internet access at specific times or days.
60. Reliable • We need instant loading offline • 60% of mobile connection is 2G • Fast Application is UX • 14 sec to load average website on 4g • 19 sec to load average website on 3G
61. Service Workers
62. Service Workers
63. Service Workers Service Workers
64. Service Workers • Rich offline experiences • Background syncs • Push notifications • …
65. Service Workers • Script that browser runs in background, separated from web page • It is Javascript worker, so it cannot access to DOM directly • Service worker is a programmable network proxy, allowing you to control how network requests from your page are handled.
66. Service Workers • It's terminated when not in use, and restarted when it's next needed, so you cannot rely on global state within a service worker's onfetch and onmessage handlers. • Service workers make extensive use of promises • Service worker is for second load
67. Service Workers lifecycle
68. Register a Service Worker if ('serviceWorker' in navigator) { window.addEventListener('load', function() { navigator.serviceWorker.register('/sw.js').then(function(registration) { // Registration was successful console.log('ServiceWorker registration successful with scope: ', registration.scope); }, function(err) { // registration failed :( console.log('ServiceWorker registration failed: ', err); }); }); }
70. Service workers Events • On install - as a dependency • On install - not as a dependency • On activate • On user interaction • On network response • Stale-while-revalidate • On push message • On background-sync
71. On install - as a dependency
72. On install - as a dependency self.addEventListener('install', function(event) { event.waitUntil( caches.open('mysite-static-v3').then(function(cache) { return cache.addAll([ '/css/whatever-v3.css', '/css/imgs/sprites-v6.png', '/css/fonts/whatever-v8.woff', '/js/all-min-v4.js' // etc ]); }) ); });
73. On install - not as a dependency
74. On install - not as a dependency self.addEventListener('install', function(event) { event.waitUntil( caches.open('mygame-core-v1').then(function(cache) { cache.addAll( // levels 11-20 ); return cache.addAll( // core assets & levels 1-10 ); }) ); });
75. Update Service Worker • Update your service worker JavaScript file. When the user navigates to your site, the browser tries to redownload the script file that defined the service worker in the background. If there is even a byte's difference in the service worker file compared to what it currently has, it considers it new. • Your new service worker will be started and the install event will be fired. • At this point the old service worker is still controlling the current pages so the new service worker will enter a waiting state. • When the currently open pages of your site are closed, the old service worker will be killed and the new service worker will take control. • Once your new service worker takes control, its activate event will be fired.
77. self.addEventListener('activate', function(event) { event.waitUntil( caches.keys().then(function(cacheNames) { return Promise.all( cacheNames.filter(function(cacheName) { // Return true if you want to remove this cache, // but remember that caches are shared across // the whole origin }).map(function(cacheName) { return caches.delete(cacheName); }) ); }) ); }); On Activate
78. Update Service Worker • self.skipWaiting() • Skips waiting for refresh to start using new SW
79. On User Interaction
80. // on user interaction document.querySelector('.cache-article').addEventListener('click', function(event) { event.preventDefault(); var id = this.dataset.articleId; caches.open('mysite-article-' + id).then(function(cache) { fetch('/get-article-urls?id=' + id).then(function(response) { // /get-article-urls returns a JSON-encoded array of // resource URLs that a given article depends on return response.json(); }).then(function(urls) { cache.addAll(urls); }); }); });
81. On Network response
82. self.addEventListener('fetch', function(event) { event.respondWith( caches.open('mysite-dynamic').then(function(cache) { return cache.match(event.request).then(function (response) { return response || fetch(event.request).then(function(response) { cache.put(event.request, response.clone()); return response; }); }); }) ); });
83. State-while-revalidate
84. State-while-revalidate self.addEventListener('fetch', function(event) { event.respondWith( caches.open('mysite-dynamic').then(function(cache) { return cache.match(event.request).then(function(response) { var fetchPromise = fetch(event.request).then(function(networkResponse) { cache.put(event.request, networkResponse.clone()); return networkResponse; }) return response || fetchPromise; }) }) ); });
85. On Background Sync
86. self.addEventListener('sync', function(event) { if (event.id == 'update-leaderboard') { event.waitUntil( caches.open('mygame-dynamic').then(function(cache) { return cache.add('/leaderboard.json'); }) ); } });
87. SW: Serving suggestions - responding to requests • Cache only • Network only • Cache, falling back to network • Cache & network race • Network falling back to cache • Cache then network • Generic fallback
88. Cache only
89. Cache only self.addEventListener('fetch', function(event) { // If a match isn't found in the cache, the response // will look like a connection error event.respondWith(caches.match(event.request)); });
90. Network only
91. Network only self.addEventListener('fetch', function(event) { event.respondWith(fetch(event.request)); // or simply don't call event.respondWith, which // will result in default browser behaviour });
92. Cache, falling back to network
93. Cache, falling back to network self.addEventListener('fetch', function(event) { event.respondWith( caches.match(event.request).then(function(response) { return response || fetch(event.request); }) ); });
94. Cache & network race
95. Cache & network race // Promise.race is no good to us because it rejects if // a promise rejects before fulfilling. Let's make a proper // race function: function promiseAny(promises) { return new Promise((resolve, reject) => { // make sure promises are all promises promises = promises.map(p => Promise.resolve(p)); // resolve this promise as soon as one resolves promises.forEach(p => p.then(resolve)); // reject if all promises reject promises.reduce((a, b) => a.catch(() => b)) .catch(() => reject(Error("All failed"))); }); }; self.addEventListener('fetch', function(event) { event.respondWith( promiseAny([ caches.match(event.request), fetch(event.request) ])
96. Network, falling back to Cache
97. Network, falling back to Cache self.addEventListener('fetch', function(event) { event.respondWith( fetch(event.request).catch(function() { return caches.match(event.request); }) ); });
98. Cache, than Network
99. Cache, than Network var networkDataReceived = false; startSpinner(); // fetch fresh data var networkUpdate = fetch('/data.json').then(function(response) { return response.json(); }).then(function(data) { networkDataReceived = true; updatePage(data); }); // fetch cached data caches.match('/data.json').then(function(response) { if (!response) throw Error("No data"); return response.json(); }).then(function(data) { // don't overwrite newer network data if (!networkDataReceived) { updatePage(data); } }).catch(function() { // we didn't get cached data, the network is our last hope: return networkUpdate; }).catch(showErrorMessage).then(stopSpinner);
100. Cache, than Network self.addEventListener('fetch', function(event) { event.respondWith( caches.open('mysite-dynamic').then(function(cache) { return fetch(event.request).then(function(response) { cache.put(event.request, response.clone()); return response; }); }) ); });
101. Generic fallback
102. Generic fallback self.addEventListener('fetch', function(event) { event.respondWith( // Try the cache caches.match(event.request).then(function(response) { // Fall back to network return response || fetch(event.request); }).catch(function() { // If both fail, show a generic fallback: return caches.match('/offline.html'); // However, in reality you'd have many different // fallbacks, depending on URL & headers. // Eg, a fallback silhouette image for avatars. }) ); });
106. Reliable conclusion • Think how you design for the success, failure and instability of a network connection • Data may be expensive, so be considerate to the user • Make sure performance is part of your design process and UX • Try to provide offline by default if your app doesn't require much data • Inform users of their current state and of changes in states • https://serviceworke.rs/ - different examples
107. https://serviceworke.rs/ - different examples
108. Your goal is to provide a good experience that lessens the impact of changes in connectivity
109. Fast Integrated Reliable Engaging
110. Engaging • Charming and Attractive • Shift way how we think in patterns and designs from web patterns to some native patterns • Push notifications (browser doesn’t need to be opened) • Push Notification API
111. Engaging
112. What makes good notification Push. Push. Back upon now. (Courtesy Enrique Iglesias)
113. What makes good notification • Timely - I feel I need and it matters now • Precise - specific info, what happens • Personal - make it personal
114. What makes good notification
115. https://www.slideshare.net/SeulgiChoi4/pwa-push-notification
116. https://www.slideshare.net/SeulgiChoi4/pwa-push-notification
118. self.addEventListener('push', function(event) { if (event.data.text() == 'new-email') { event.waitUntil( caches.open('mysite-dynamic').then(function(cache) { return fetch('/inbox.json').then(function(response) { cache.put('/inbox.json', response.clone()); return response.json(); }); }).then(function(emails) { registration.showNotification("New email", { body: "From " + emails[0].from.name tag: "new-email" }); }) ); } }); self.addEventListener('notificationclick', function(event) { if (event.notification.tag == 'new-email') { // Assume that all of the resources needed to render // /inbox/ have previously been cached, e.g. as part // of the install handler. new WindowClient('/inbox/'); } });
119. Push Notifications { "body": "Did you make a $1,000,000 purchase at Dr. Evil...", "icon": "images/ccard.png", "vibrate": [200, 100, 200, 100, 200, 100, 400], "tag": "request", "actions": [ { "action": "yes", "title": "Yes", "icon": "images/yes.png" }, { "action": "no", "title": "No", "icon": "images/no.png" } ] }
120. 43% agrees to an app’s request to allow push notifications
122. Tools!
123. Lighthouse
125. Some show case!
126. 65% increase in page per session 75% increase in Tweets sent
 20% decrease in bounce rate Twitter Lite
127. 76% higher conversation across browsers 4x higher interaction rate from Add to screen Increased usage of native apps also Alibaba
128. 80%+ conversation 54% smaller than Android app 120% smaller than iOS app BookMyShow
129. Cut load times from 11.91 to 4.69 seconds 90% smaller than Native Android App https://medium.com/@addyosmani/a-tinder-progressive-web-app-performance- case-study-78919d98ece0 Tinder
130. Myths about PWA!
131. PWAs are only for offline apps
132. PWAs are a mobile thing
133. PWAs are a Google-only thing
135. PWAs are not ready yet
140. https://pwa.rocks/
143. Don’t be driven with hype, choose the best fit for your project
144. It is not about PWA vs Native apps, it is about Users
145. Thank you!
146. QnA? 1st question will get free ticket for BločkConf (workshop + conference) Join us at BločkConf! 14-15.12.
 www.blockconf.io Use ‘growit’ code for 20% discount