The Step-By-Step Process For Converting A React App with Flask Backend to a PWA

I've always been fascinated by the idea of making web apps feel more like native mobile apps. That's why I want to share with you how you can turn your React App with Flask backend into a Progressive Web App (PWA). With PWAs, users can enjoy features like offline access, push notifications, and improved performance, which can greatly enhance their experience. So let's get started with Converting A React App with Flask Backend to a PWA!

Introduction to Progressive Web Apps (PWA)

Before diving into the conversion process, let's take a moment to understand what Progressive Web Apps are.

Progressive Web Apps (PWA) are web apps that provide a native-like experience to users, offering features like offline access, push notifications, and high performance. PWAs use modern web capabilities to deliver an app-like experience to users across all devices.

Benefits of converting React App to PWA

Converting your React App to a PWA offers several benefits, including:

1. Improved performance: PWAs are designed to be fast and responsive, providing a seamless user experience. They use features like service workers and lazy loading to optimize performance.

2. Offline access: With PWAs, users can access your app even when they are offline. This is achieved through the use of service workers, which cache the app's assets and content.

3. Increased user engagement: PWAs offer features like push notifications and home screen installation, which can increase user engagement and retention.

The step-by-step process for converting React App with Flask backend to PWA

Now that we understand the benefits of converting React App to PWA, let's dive into the conversion process. Here is a step-by-step guide to help you through the process:

Step 1: Set up a manifest.json file:

The manifest.json file is a file that tells the browser how to display your PWA. It includes information such as the app name, icons, and theme color.

In your React app, create a file named manifest.json in the public folder and paste the following code into the file. You can modify things according to your app.

manifest.json

{
  "short_name": "My PWA",
  "name": "My PWA",
  "icons": [
    {
      "src": "favicon.ico",//add your favicon path
      "sizes": "64x64 32x32 24x24 16x16",
      "type": "image/x-icon"
    },
    {
      "src": "logo.png",//add your logo path
      "type": "image/png",
      "sizes": "192x192"
    },
    {
      "src": "logo.png", //add your logo path
      "type": "image/png",
      "sizes": "512x512"
    }
  ],
  "scope": "/",
  "start_url": "/",
  "display": "standalone",
  "theme_color": "#000000",
  "background_color": "#ffffff"
}

Step 2: Add the service worker file in the Flask backend

A service worker is a script that runs in the background and handles caching, push notifications, and offline support.

If you are using Flask backend with React app, you might face an issue with service worker not being registered with the localhost. This occurs due to the fact that if you have your React app and your Flask app running on different ports usually localhost:3000 for React app and localhost:5000 for Flask server, redirect issues happen .

The service worker script is expected to be on the absolute path of the application by default. To fix this, we need to serve the service worker file from the server.

So in your server, add the serviceWorker.js file in the project folder and include the following code in your serviceWorker.js file

This steps work with Quart backend as well. Although both Quart and Flask are excellent choices for web development, it's essential to recognize that they share similarities while also presenting nuanced distinctions. Understanding these subtle differences is crucial to harnessing the full potential of these powerful Python web frameworks.

serviceWorker.js

const cacheName = "MyAppCache"
const assets = [
  "/"
]

self.addEventListener("install", installEvent => {
  installEvent.waitUntil(
    caches.open(cacheName ).then(cache => {
      cache.addAll(assets)
    })
  )
})

In your server.py file in flask add the following code to serve the serviceWorker.js file when called from the React app.

server.py

If you are using Quart

#import make_response and send_from_directory from Quart
from quart import Quart,make_response,send_from_directory

#Route to get the serviceWorker file
@app.route('/serviceWorker.js')
async def get_service_worker():
    #in this case serviceWorker.js is stored in the root of the project
    #You can enter the name of directory in which this file is stored
    filePath = await send_from_directory('', 'serviceWorker.js')
    response = await make_response(filePath)
    response.headers['Content-Type'] = 'application/javascript'
    return response

If you are using Flask

#import make_response and send_from_directory from Quart
from flask import Flask,make_response,send_from_directory

#Route to get the serviceWorker file
@app.route('/serviceWorker.js')
def get_service_worker():
    #in this case serviceWorker.js is stored in the root of the project
    #You can enter the name of directory in which this file is stored
    response = make_response(send_from_directory('','serviceWorker.js'))
    response.headers['Content-Type'] = 'application/javascript'
    return response

Step 3: Register the service worker in your React app

In your React App, register the service worker in index.js file.

index.js

if ('serviceWorker' in navigator) {
    window.addEventListener('load', function() {
      navigator.serviceWorker.register('/serviceWorker.js');
    });
  }

then the complete file becomes

import React from "react";
import ReactDOM from "react-dom/client";
import "./index.css";
import App from "./App";
import reportWebVitals from "./reportWebVitals";

const root = ReactDOM.createRoot(document.getElementById("root"));
root.render(
  <React.StrictMode>
    <App />
  </React.StrictMode>
);

// If you want to start measuring performance in your app, pass a function
// to log results (for example: reportWebVitals(console.log))
// or send to an analytics endpoint. Learn more: https://bit.ly/CRA-vitals
reportWebVitals();

//Register the service worker
if ('serviceWorker' in navigator) {
    window.addEventListener('load', function() {
      navigator.serviceWorker.register('/serviceWorker.js');
    });
  }

Step 4: Test the PWA

You can test the PWA by running the react app using ngrok to test it on your mobile device.

Conclusion

In conclusion, converting your React App with Flask to a PWA can provide a more native-like experience to your web users. By following the step-by-step process outlined in this article, you can create a PWA that offers features like offline access, push notifications, and high performance.

If you are interested in learning more about PWAs and Flask backend, I recommend checking out the official documentation for each technology. Happy coding!