The Reasons Behind Having Your Website Function Offline (And What To Do About It)
Tags: webdev, javascript, tutorial, beginners
Published: 2023-12-08 08:01:57

You read correctly. Not online! Strange, sweetie?

However, there are a lot of reasons why you would want to.

Web applications with offline capability let users use and interact with the app without an internet connection.

This can greatly improve the user experience, especially in situations when internet connectivity is spotty or nonexistent.


![Image description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/cb41uijdebgoxgtv0hw9.gif)

🫵 Can you confirm that this is a real thing? 

Here are some instances of actual applications for offline functionality:

**1. Apps for Reading News and Articles**
Consider a news app that lets users bookmark articles to read later.

When connected to the internet, the programme pre-fetches and caches articles that the user is interested in.

Later, whether the user is on a plane or in a place with weak access, they can still read these articles seamlessly.

For example, the New York Times app makes it easy for consumers to access material at any time by providing offline reading tools.

**2. Applications for E-Commerce**
When a user isn't online, e-commerce apps can take advantage of offline functionality to let them browse products and add them to their cart.

When the user regains internet connectivity, their cart can be synced with the server.

This strategy can enhance the purchasing experience, reducing the loss of possible sales due to connectivity troubles.

**3. Applications for Navigation and Travel**
When they operate offline, travel apps—especially those with maps and navigation—can be very helpful.

Users can download maps or routes while they have an internet connection and then use the app for navigation when they are in areas without mobile data access.

Google Maps, for example, allows users to download certain locations for offline use.

**4. Learning and Instructional Websites**
Courses, tutorials, and learning resources can be accessed offline with the use of educational applications.

This is especially helpful for people who wish to continue learning while commuting or travelling, as well as for those who live in areas with poor internet connectivity.

When online, users can download courses or lessons, which they can view later without requiring an internet connection.

**5. Note-taking and Productivity Apps**
With offline capability, productivity apps such as note-taking or task-management software enable users to take and modify notes or manage projects even when they are not connected to the internet.

Once the device is connected to the internet again, changes performed offline can be synchronised back to the server, guaranteeing no loss of data or productivity.

**6. Entertainment and Streaming Services**
Streaming services like Netflix and Spotify allow choices to download content like movies, episodes, or music when connected to Wi-Fi, which customers may then enjoy later without needing an internet connection.

This function is especially helpful for on-the-go entertainment, such as in places with sporadic access or on aeroplanes.

**🫵 Ok, I'm convinced. How am I going to do that?**

A service worker is usually used to cache key resources and offer them to the user when they are offline in order to implement offline functionality.

Here's a simple example that shows you how to accomplish this:

**1. Signing up for the service provider**
The service worker must first be registered in your main JavaScript file.

This is often done in your web application's entry point, which in a React app is the index.js file.

```
if ('serviceWorker' in navigator) {
  window.addEventListener('load', () => {
    navigator.serviceWorker.register('/serviceWorker.js')
      .then(registration => {
        console.log('Service Worker registered with scope:', registration.scope);
      })
      .catch(err => {
        console.log('Service Worker registration failed:', err);
      });
  });
}
```
**2. Establishing serviceWorker.js, the service worker**
Your application's caching technique is defined in the service worker file. This is a basic illustration of a script for a service worker:

```
const CACHE_NAME = 'my-site-cache';
const urlsToCache = [
  '/',
  '/styles/main.css',
  '/script/main.js',
  '/offline.html'
];

self.addEventListener('install', event => {
  event.waitUntil(
    caches.open(CACHE_NAME)
      .then(cache => {
        console.log('Opened cache');
        return cache.addAll(urlsToCache);
      })
  );
});

self.addEventListener('fetch', event => {
  event.respondWith(
    caches.match(event.request)
      .then(response => {
        // Cache hit - return response
        if (response) {
          return response;
        }
        return fetch(event.request).catch(() => caches.match('/offline.html'));
      })
  );
});
```
Within this screenplay:

- Important resources are pre-cache by the install event listener.

- When offline, the cached content is served by the fetch event listener. It provides a fallback page (such as offline.html) if a request is not in the cache and the user is not connected.

You can enjoy a rudimentary offline experience with this configuration. A more complex service worker configuration would probably be used in a real-world application to manage various caching techniques for various resource kinds (such as HTML, CSS, JavaScript, and pictures) and dynamically update the cache as necessary.


👵 lengthy post But I read it.
Congrats! I'll be happy even if this post only taught you one new idea or concept. I appreciate you taking the time to read it.

Rajesh Natarajan.