progressive-web-app

frameworkSafeIntermediateClaude

🤖 AI Summary

This skill scaffolds a Progressive Web App by generating a service worker, web app manifest, and caching strategy (e.g., via Workbox) to enable offline functionality and installability. It triggers on keywords like "PWA," "service worker," or "add to home screen."

How to Install

This skill comes from a community source.

Progressive Web Apps (PWAs)

Overview

A Progressive Web App is a web application that uses modern browser capabilities to deliver a fast, reliable, and installable experience — even on unreliable networks. The three required pillars are:

HTTPS — Required in production for service workers to register (localhost is exempt for development).
Web App Manifest (manifest.json) — Makes the app installable and defines its appearance on device home screens.
Service Worker (sw.js) — A background script that intercepts network requests, manages caches, and enables offline functionality.

When to Use This Skill

Use when the user wants their web app to work offline or on unreliable networks.
Use when building a mobile-first web project where users should be able to install the app to their home screen.
Use when the user asks about caching strategies, service workers, or improving web app performance and resilience.
Use when the user mentions Workbox, web app manifests, background sync, or push notifications for the web.
Use when the user asks "can my website be installed like an app?" or "how do I make my site work offline?" — even if they don't use the word PWA.

Deliverables Checklist

Every PWA implementation must include these files at minimum:

[ ] index.html — Links manifest, registers service worker
[ ] manifest.json — Full app metadata and icon set
[ ] sw.js — Service worker with install, activate, and fetch handlers
[ ] app.js — Main app logic with SW registration and install prompt handling
[ ] offline.html — Fallback page shown when navigation fails offline (required — missing file will cause install to fail)

Step 1: Web App Manifest (`manifest.json`)

Defines how the app appears when installed. Must be linked from <head> via <link rel="manifest">.

{
  "name": "My Awesome PWA",
  "short_name": "MyPWA",
  "description": "A fast, offline-capable Progressive Web App.",
  "start_url": "/",
  "scope": "/",
  "display": "standalone",
  "orientation": "portrait-primary",
  "background_color": "#ffffff",
  "theme_color": "#0055ff",
  "icons": [
    {
      "src": "/assets/icons/icon-192x192.png",
      "sizes": "192x192",
      "type": "image/png",
      "purpose": "any maskable"
    },
    {
      "src": "/assets/icons/icon-512x512.png",
      "sizes": "512x512",
      "type": "image/png",
      "purpose": "any maskable"
    }
  ],
  "screenshots": [
    {
      "src": "/assets/screenshots/desktop.png",
      "sizes": "1280x720",
      "type": "image/png",
      "form_factor": "wide"
    }
  ]
}

Key fields: - display: standalone hides browser UI; minimal-ui shows minimal controls; browser is standard tab. - purpose: "maskable" on icons enables adaptive icons on Android (safe zone matters — keep content in center 80%). - screenshots is optional but required for Chrome's enhanced install dialog on desktop.

Step 2: HTML Shell (`index.html`)

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>My Awesome PWA</title>

  <!-- PWA manifest -->
  <link rel="manifest" href="/manifest.json">

  <!-- Theme color for browser chrome -->
  <meta name="theme-color" content="#0055ff">

  <!-- iOS-specific (Safari doesn't fully use manifest) -->
  <meta name="apple-mobile-web-app-capable" content="yes">
  <meta name="apple-mobile-web-app-status-bar-style" content="default">
  <meta name="apple-mobile-web-app-title" content="MyPWA">
  <link rel="apple-touch-icon" href="/assets/icons/icon-192x192.png">

  <link rel="stylesheet" href="/styles.css">
</head>
<body>
  <div id="app">
    <header><h1>My PWA</h1></header>
    <main id="content">Loading...</main>
    <!-- Optional: install button, hidden by default -->
    <button id="install-btn" hidden>Install App</button>
  </div>
  <script src="/app.js"></script>
</body>
</html>

Step 3: Service Worker Registration & Install Prompt (`app.js`)

```javascript // ─── Service Worker Registration ─────────────────────────────────────────── if ('serviceWorker' in navigator) { window.addEventListener('load', async () => { try { const registration = await navigator.serviceWorker.register('/sw.js'); console.log('[App] SW registered, scope:', registration.scope); } catch (err) { console.error('[App] SW registration failed:', err); } }); }

// ─── Install Prompt (Add to Home Screen) ─────────────────────────────────── let deferredPrompt; const installBtn = document.getElementById('install-btn'); // may be null if omitted

// Capture the browser's install prompt — it fires before the browser's own UI window.addEventListener('beforeinstallprompt', (e) => { e.preventDefault(); // Stop automatic mini-infobar on mobile deferredPrompt = e; if (installBtn) installBtn.hidden = false; // Show your custom install button });

if (installB

UI/UX

Details

Category	Frontend → framework
Source	community
SKILL.md	View on GitHub →
Repo Stars	N/A
Est. per Skill	N/A (shared across 1230 skills from this repo)
Difficulty	Intermediate
Risk Level	Safe