Tapajyoti Bose

Posted on Apr 18, 2021 • Edited on Oct 24, 2023

Supercharge Your Website Using PWA: Installable Website

#pwa #webdev #ux #javascript

What is a `PWA`?

Progressive Web Apps (PWA) are web applications that have been designed so they are capable (utilize native features), reliable (work even in offline mode), and installable. These three pillars transform them into an experience that feels like a platform-specific application.

Why use `PWA`?

At their heart, Progressive Web Apps are just web applications. Using progressive enhancement, new capabilities are enabled in modern browsers. Using service workers and a web app manifest, a web application can be converted into a PWA. If the new capabilities aren't available, users still get the core experience.

As it can be seen from the picture above, PWA offers the best of both worlds by delivering a web experience your users will love, using the latest web features to bring enhanced capabilities and reliability, Progressive Web Apps allow what you build to be installed by anyone, anywhere, on any device with a single codebase.

Getting Started

The requirements for a website to be turned into a PWA are:

The website itself (served over https or from localhost)
manifest.json (provides information about a web application)
service worker (a script that allows intercepting and control of how a web browser handles its network requests and asset caching.)

Here we will not be focusing on creating a website, but on making an existing website installable. To follow along just use a basic website like the one given below.

<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8" />
        <meta http-equiv="X-UA-Compatible" content="IE=edge" />
        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
        <title>PWA: Installable website</title>
    </head>
    <body>
        <h1>Test</h1>
    </body>
</html>

NOTE: Its possible to style the site or add scripts, but for the purpose of adding PWA installation feature, this will suffice.

The defination of manifest.json

{
  "name": "<name of the application>",
  "short_name": "<short name for the application> (can be same as name)",
  "start_url": "<start url for the website>",
  "display": "<display mode for the website>",
  "description": "<description of the application>",
  "background_color": "<color>",
  "theme_color": "<color>",
  "orientation": "<orientation>",
  "icons": [{
    "src": "<image source>",
    "sizes": "<widthxheight>",
    "type": "image/png"
  }]
}

An example manifest.json would look like

{
    "name": "PWA: Installable website",
    "short_name": "Installable PWA",
    "start_url": "index.html",
    "display": "standalone",
    "description": "App for testing PWA features",
    "background_color": "#ffffff",
    "theme_color": "#000000",
    "orientation": "portrait-primary",
    "icons": [
        {
            "src": "image/icon-24.png",
            "sizes": "24x24",
            "type": "image/png"
        },
        {
            "src": "image/icon-32.png",
            "sizes": "32x32",
            "type": "image/png"
        },
        {
            "src": "image/icon-48.png",
            "sizes": "48x48",
            "type": "image/png"
        },
        {
            "src": "image/icon-64.png",
            "sizes": "64x64",
            "type": "image/png"
        },
        {
            "src": "image/icon-128.png",
            "sizes": "128x128",
            "type": "image/png"
        },
        {
            "src": "image/icon-256.png",
            "sizes": "256x256",
            "type": "image/png"
        }
    ]
}

To add the manifest to the website, add the following in the head section

<link rel="manifest" href="manifest.json" />

Its a good practice to add the following in the head section as well for iOS support

<link rel="apple-touch-icon" href="image/icon-24.png" />
<link rel="apple-touch-icon" href="image/icon-32.png" />
<link rel="apple-touch-icon" href="image/icon-48.png" />
<link rel="apple-touch-icon" href="image/icon-64.png" />
<link rel="apple-touch-icon" href="image/icon-72.png" />
<link rel="apple-touch-icon" href="image/icon-96.png" />
<link rel="apple-touch-icon" href="image/icon-128.png" />
<link rel="apple-touch-icon" href="image/icon-256.png" />
<meta name="apple-mobile-web-app-status-bar" content="#db4938" />
<meta name="theme-color" content="#db4938" />

Now only the service worker is left to be dealt with.

service-worker.js

const STATIC_CACHE = "static-cache-v1"
const static_assets = [
    "/",
    "/index.html",
    "/script.js",
    "/image/icon-24.png",
    "/image/icon-32.png",
    "/image/icon-48.png",
    "/image/icon-64.png",
    "/image/icon-72.png",
    "/image/icon-96.png",
    "/image/icon-128.png",
    "/image/icon-256.png",
]

// storing static assets in cache on service worker install
self.addEventListener("install", event => {
    event.waitUntil(
        caches.open(STATIC_CACHE).then(cache => {
            cache.addAll(static_assets)
        })
    )
})

// returning static assets from cache
self.addEventListener("fetch", event => {
    event.respondWith(
        caches.match(event.request).then(response => {
            return response || fetch(event.request);
        })
    )
});

We are required to handle the fetch event to enable installation.

Enable the service worker by adding the following script in the website

<script>
    if ('serviceWorker' in navigator) {
        navigator.serviceWorker.register('/service-worker.js');
    } else {
        console.log("Service worker is not supported");
    }
</script>

Now the last piece of the puzzle, serving the website on localhost. If you are using VS Code, you can easily do it using the live server extension (recommended for beginners).

The installation icon on the top right of the url-bar signifies its now installable. Click it to install the pwa on your device.

NOTE: This is just a brief overview. In a production grade pwa its more advisible to periodically refresh the static assets as well to ensure that the user don't access outdated content.

Project using this Implementation

Smartsapp

Web-app: https://smartsapp-ba40f.firebaseapp.com

ruppysuppy / SmartsApp

💬📱 An End to End Encrypted Cross Platform messenger app.

Smartsapp

A fully cross-platform messenger app with End to End Encryption (E2EE).

Demo

NOTE: The features shown in the demo is not exhaustive. Only the core features are showcased in the demo.

Platforms Supported

Desktop: Windows, Linux, MacOS
Mobile: Android, iOS
Website: Any device with a browser

Back-end Setup

The back-end of the app is handled by Firebase.

Basic Setup

Go to firebase console and create a new project with the name Smartsapp
Enable Google Analylitics

App Setup

Create an App for the project from the overview page
Copy and paste the configurations in the required location (given in the readme of the respective apps)

Auth Setup

Go to the project Authentication section
Select Sign-in method tab
Enable Email/Password and Google sign in

Firestore Setup

Go to the project Firestore section
Create firestore provisions for the project (choose the server nearest to your location)
Go to the Rules…

View on GitHub

Reference

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Thanks for reading

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Top comments (11)

Dor Shinar • Apr 18 '21

PWA is really sweet, and for a long I was sure it was going to be the future, but now I begin to doubt it.
On my phone I have exactly one app that is a PWA (dev.to), and most people I know have zero PWAs, even though they have close to 100 regular apps.
I think people are used to installing apps from stores (the App Store or the Play Store), and are very hesitant to "install" a web site (which, admittedly sound a bit suspicious).