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Codelab Flow

What we shall do

L P Progressive Web Apps

We are going to create a progressive web app with our html5 template. Unzip the downloaded file to your prefered location after download. If you have Github Desktop installed, simply fork and/or clone it.

What you will need

Make sure you have all this checked before we start.

Create service worker and manifest

In our template's work folder; go to the app/ folder and add two empty files namely service-worker.js and app.webmanifest respectively and save.

Register the service worker

This is the first step to making our web app work offline. Copy and paste this code to the index.html in our app/ folder just before the end of the body tag or in the head tag.

N/B : YOU NEED HTTPS : We are going to use Firebase Hosting later which shall have HTTPS already provisioned for our project.

This code checks to see if the service worker API is available, and if it is, the service worker at ./service-worker.js is registered once the page is loaded.
First, we need to check if the browser supports service workers, and if it does, register the service worker.

    <!-- register service worker -->
    if ('serviceWorker' in navigator) 
          window.addEventListener('load', () => {
          .then(() => { console.log("[ PWA Fire Bundle ] Service Worker Registered"); });
        } ); 

Using the web manifest

We are going to add a link tag to all the pages that encompass our web app inside the head tag, as follows; For our case, we only have one page, the index.html. Add the following code to it.

      <!-- start of web manifest -->
      <link rel="manifest" href="./app.webmanifest">
      <!-- end of web manifest -->

Service Worker

NOTE : The important thing to understand about the Service Worker is that you are in control of the network. You get to decide what is cached, how it is cached and how it should be returned to the user.

A Service Worker opens doors to new capabilities e.gpush notification, add to homescreen, sharable etc
Follow the steps as commented in the code below in order to correctly configure the ./service-worker.js file.
            // Fetch events, on registration of Service Worker...
self.addEventListener('fetch', (event) => {
  event.respondWith('cache').then((cache) => {
    return cache.match(event.request).then((response) => {
      console.log("cache request: " + event.request.url);
       var fetchPromise = fetch(event.request).then((networkResponse) => {           
// Update the cache...                   
console.log("fetch completed: " + event.request.url, networkResponse);
  if (networkResponse) {
    console.debug("updated cached page: " + event.request.url, networkResponse);
      cache.put(event.request, networkResponse.clone());}
        return networkResponse;
          }, event => {   
// Rejected promise - just ignore it, we're offline...  
          console.log("Error in fetch()", event);
// Name the *cache* in the
'cache').then((cache) => { 
          // Take a list of URLs, then fetch them from the server and add the response to the cache...
          return cache.addAll([                    
// Respond from the cache, or the network...
  return response || fetchPromise;

// Always updating i.e latest version available...
self.addEventListener('install', (event) => {
    console.log("Latest version installed!");

Web Manifest

Configure/edit the background and theme colors, display type, the PWA short name (any name), the Web App name, icons size (icons in the icons folder are already in the required sizes) and your icon/logo paths.

We have to state the img type eg image/ico or image/png. This is already done for you. You could use your own icons or logos and update later after this codelab.

Leave the start url as it is though this can be any page or source directory in your web app; the value we’re using has the advantage of being meaningful to Google Analytics.

Configuring the app.webmanifest file helps you to specify how you want your web app to look like when launched on the device.
Configure the app.webmanifest file as directed above in order to fit your web app needs.
          "background_color": "#fff",
          "display": "standalone",
          "theme_color": "#fff",           
          "short_name": "PWA Name",
          "name": "PWA Name",
          "description": "Description or purpose of your PWA",
          "lang": "en-US",
          "icons": [
            "src": "images/icons/icon-192x192.png",
            "sizes": "192x192",
            "type": "image/png"
            "src": "images/icons/icon-512x512.png",
            "sizes": "512x512",
            "type": "image/png"
          "start_url": "index.html?launcher=true"

In the head tag, add theme color to all your pages as shown in the code below; You could use the same theme colour as in the ./app.webmanifest file.

        <!-- theme-color -->
        <meta name="theme-color" content="#fff" />
        <!-- end-theme-color -->

Preview PWA

Use your favourite web server to view your Progressive Web App in Google Chrome. You should be able to have your PWA work offline and insallable on desktop and on mobile device if you host it somewhere or deploy to firebase hosting as shown below.

Firebase Hosting

If you're new to Firebase, you'll need to create your account and install some tools first. Install latest version of node.js first

1. Create a Firebase account at Once your account has been created and you've signed in, you're ready to deploy!

2. Create a new Firebase app at

3. Install the Firebase tools via npm (run this in your command line).The Firebase Command Line Interface (CLI) will allow you to serve the web app locally and deploy.

npm -g install firebase-tools

4. To verify that the CLI has been installed correctly, open a console and run:

firebase --version

5. If you haven't recently signed in to the Firebase tools, update your credentials:

firebase login

6. Make sure you are in the /app folder (which is our project root folder i.e where our index.html is) then Initialize your app to use Firebase. Select your Project ID and follow the instructions.

When prompted, you can choose any Alias, such as pwafire for instance. Select Firebase Hosting as the Firebase CLI feature. Provide the default directory as /. To the other prompts, reply NO; N

firebase init

7. Let's serve and test the firebase project locally. Run the following command from the root of your local project directory.

firebase serve

8. Finally, deploy the app to Firebase:

firebase deploy

9. Celebrate. You're done! Your app will be deployed to the domain:

10. Visit your web app on your phone now. You should see an "install to homescreen" banner prompt! Welcome to PWAs World! Further reading: Firebase Hosting Guide.

Mr. PWA Fire's Son Dance Mr. PWA Fire's Son Dance