Progressive Web Apps for Rails developers

Progressive Web Apps for R a ils developers Emm a
nuel H a yford R a ils Ch a ngelog Podc a st Host @si a w23

App a v a il a bility with fl a
ky/no internet connections Push Noti fi c a tions F a st lo a d times No middlem a n with a pp downlo a ds/inst a ll a tion S a ve money on dedic a ted n a tive a pp dev te a m Why should you consider PWAs with R a ils?

Why should consider PWAs with R a ils? source: https://www.pw
a st a ts.com

“I don’t w a nn a use Apple stu ff
a nymore… the fi n a l str a w w a s when Apple s a id ‘we’re gonn a pull PWAs outt a Europe.’” - DHH vi a How About Tomorrow Podc a st

PWA Requirements Service worker Secure context Web a pplic a
tion m a nifest

<!DOCTYPE html> <html> <head> </head> <body> </body>
</html>

<!DOCTYPE html> <html> <head> <%= tag.link rel:
"manifest", href: pwa_manifest_path(format: :json) %> </head> <body> </body> </html>

# config/routes.rb Rails.application.routes.draw do end

# config/routes.rb Rails.application.routes.draw do get "manifest" => "rails/pwa#manifest", as: :pwa_manifest
get "service-worker" => "rails/pwa#service_worker", as: :pwa_service_worker end

// app/javascript/application.js if ("serviceWorker" in navigator) { }

// app/javascript/application.js if ("serviceWorker" in navigator) { // Register a
service worker hosted at the root of the // app using the default scope. navigator.serviceWorker.register("/service-worker.js") }

service worker hosted at the root of the // app using the default scope. navigator.serviceWorker.register("/service-worker.js").then( (registration) => { console.log("Service worker registration succeeded:", registration); } }

service worker hosted at the root of the // app using the default scope. navigator.serviceWorker.register("/service-worker.js").then( (registration) => { console.log("Service worker registration succeeded:", registration); }, (error) => { console.error(`Service worker registration failed: ${error}`); } ); } }

service worker hosted at the root of the // app using the default scope. navigator.serviceWorker.register("/service-worker.js").then( (registration) => { console.log("Service worker registration succeeded:", registration); }, (error) => { console.error(`Service worker registration failed: ${error}`); } ); } else { console.error("Service workers are not supported."); }

Service Worker Lifecycle

O ffl ine & Perform a nt PWAs Cache API
HTTP Cache Fine-grained, programmatic control over what gets cached, how it's cached, and when it's updated/ deleted. The browser's HTTP cache is managed automatically based on HTTP headers (Cache-Control, Expires, ETag, etc.) provided by the server. Provides a JavaScript interface to interact with cached responses directly within the service worker. JavaScript running in the web page cannot directly access or manipulate the contents of the HTTP cache. Caches are scoped to the origin and the specific service worker, ensuring isolation between different PWAs. The HTTP cache is shared across the entire browser for a given user and origin. It is not scoped to individual applications or service workers. Offers reliable storage intended for offline use, retaining resources until the developer removes them or the browser's storage quota is exceeded. Doesn't guarantee availability when offline, especially if resources are not fresh according to cache validation rules.

// app/views/pwa/service-worker.js self.addEventListener("install", (event) => { });

// app/views/pwa/service-worker.js self.addEventListener("install", (event) => { event.waitUntil( ); });

// app/views/pwa/service-worker.js self.addEventListener("install", (event) => { event.waitUntil( caches.open("v1") ); });

// app/views/pwa/service-worker.js self.addEventListener("install", (event) => { event.waitUntil( caches.open("v1") .then((cache) =>
), ); });

// app/views/pwa/service-worker.js self.addEventListener("install", (event) => { event.waitUntil( caches.open("v1") .then((cache) =>
cache.addAll([ "/some.html", "/application.js", "/offline.html", ]), ), ); });

// app/views/pwa/service-worker.js self.addEventListener("fetch", (event) => { });

// app/views/pwa/service-worker.js self.addEventListener("fetch", (event) => { event.respondWith( ); });

// app/views/pwa/service-worker.js self.addEventListener("fetch", (event) => { event.respondWith( caches.match(event.request).then((response) => {
}), ); });

if (response !== undefined) { return response; } }), ); });

if (response !== undefined) { return response; } else { return fetch(event.request) .then((response) => { let responseClone = response.clone(); caches.open("v1").then((cache) => { cache.put(event.request, responseClone); }); return response; }) } }), ); });

if (response !== undefined) { return response; } else { return fetch(event.request) .then((response) => { let responseClone = response.clone(); caches.open("v1").then((cache) => { cache.put(event.request, responseClone); }); return response; }) .catch(() => caches.match("/offline.html")); } }), ); });

Why did the PWA bring a ladder to the apps
party? Because it wanted to take things of fl ine—but still be up to date!

BackgroundSync API IndexedDB The BackgroundSync API allows web apps to
delay sending data to the server until the device is online, with the service worker handling it in the background. IndexedDB is a low-level, large-scale, NoSQL storage system that allows storing structured data in the user's browser. IndexedDB Libraries localForage, Dexie.js, idb-keyval, PouchDb

import { set, get } from 'idb-keyval';

import { set, get } from 'idb-keyval'; set('hello', 'world') .then(()
=> console.log('It worked!')) .catch((err) => console.log('It failed!', err));

import { set, get } from 'idb-keyval'; set('hello', 'world') .then(()
=> console.log('It worked!')) .catch((err) => console.log('It failed!', err)); // logs: "world" get('hello').then((val) => console.log(val));

<%= form_with(url: "/blogs", method: :post, id: "blogForm") do %> <div>
<%= label_tag :title, "Title:" %> <%= text_field_tag :title, nil, required: true %> </div> <div> <%= label_tag :content, "Content:" %> <%= text_area_tag :content, nil, required: true %> </div> <div> <%= submit_tag "Submit" %> </div> <% end %>

// app/javascript/application.js if ('serviceWorker' in navigator) { }

// app/javascript/application.js if ('serviceWorker' in navigator && 'SyncManager' in window)
{ }

// app/javascript/application.js if ('serviceWorker' in navigator && 'SyncManager' in window)
{ navigator.serviceWorker.register('/service-worker.js') .then(registration => { // ... }) .catch(error => { // ... }); } else { // ... }

// Function to save blog to IndexedDB via idb-keyval const
saveBlogForSync = (blog) => { }; // Function to send blog data const sendBlog = (blog) => { }; // app/javascript/application.js

saveBlogForSync = (blog) => { idbKeyval.set('syncBlog', blog) }; // Function to send blog data const sendBlog = (blog) => { }; // app/javascript/application.js

saveBlogForSync = (blog) => { idbKeyval.set('syncBlog', blog) .then(() => { // Register for background sync return navigator.serviceWorker.ready; }) .then(registration => registration.sync.register('sync-blog')) .catch(error => { console.error('Sync registration failed:', error); }); }; // Function to send blog data const sendBlog = (blog) => { }; // app/javascript/application.js

saveBlogForSync = (blog) => { idbKeyval.set('syncBlog', blog) .then(() => { // Register for background sync return navigator.serviceWorker.ready; }) .then(registration => registration.sync.register('sync-blog')) .catch(error => { console.error('Sync registration failed:', error); }); }; // Function to send blog data const sendBlog = (blog) => { if (navigator.onLine) { // Send blog data immediately if online fetch('/blogs', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify(blog) }) } else { // If offline, save blog for background sync saveBlogForSync(blog); } }; // app/javascript/application.js

// app/javascript/application.js document.getElementById('blogForm').addEventListener('submit', (event) => { event.preventDefault(); });

// app/javascript/application.js document.getElementById('blogForm').addEventListener('submit', (event) => { event.preventDefault(); const blog =
{ title: document.getElementById('title').value, content: document.getElementById('content').value }; });

{ title: document.getElementById('title').value, content: document.getElementById('content').value }; sendBlog(blog); });

{ title: document.getElementById('title').value, content: document.getElementById('content').value }; sendBlog(blog); }); // Function to send blog data const sendBlog = (blog) => { if (navigator.onLine) { fetch('/blogs', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify(blog) }) } else { saveBlogForSync(blog); } };

// app/views/pwa/service-worker.js importScripts('https://url/to/idb-keyval.min.js'); self.addEventListener('sync', (event) => { });

// app/views/pwa/service-worker.js importScripts('https://url/to/idb-keyval.min.js'); self.addEventListener('sync', (event) => { if (event.tag ===
'sync-blog') { } });

'sync-blog') { event.waitUntil( idbKeyval.get('syncBlog') ); } });

'sync-blog') { event.waitUntil( idbKeyval.get('syncBlog') .then(blog => { if (blog) { return fetch('/blogs', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify(blog) }) .then(response => { if (response.ok) { } throw new Error('Network response was not ok'); }); } }) ); } });

'sync-blog') { event.waitUntil( idbKeyval.get('syncBlog') .then(blog => { if (blog) { return fetch('/blogs', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify(blog) }) .then(response => { if (response.ok) { return idbKeyval.delete('syncBlog'); } throw new Error('Network response was not ok'); }); } }) ); } });

'sync-blog') { event.waitUntil( idbKeyval.get('syncBlog') .then(blog => { if (blog) { return fetch('/blogs', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify(blog) }) .then(response => { if (response.ok) { return idbKeyval.delete('syncBlog'); } throw new Error('Network response was not ok'); }); } }) .catch(error => { console.error('Sync failed:', error); }) ); } });

# app/controllers/blogs_controller.rb class BlogsController < ApplicationController def create @blog =
Blog.new(blog_params) if @blog.save render json: { message: 'Blog created successfully' }, status: :created else render json: { message: 'Failed to create blog' }, status: :unprocessable_entity end end private def blog_params params.require(:blog).permit(:title, :content) end end

Diagram courtesy of Apple

Th a nk you! Emm a nuel H a yford
@si a w23

Progressive Web Apps for Rails developers

Progressive Web Apps for Rails developers

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