Unlocking Seamless Offline Functionality in Modern Apps
In today’s digital landscape, users expect apps to provide a seamless experience, even when internet connectivity is intermittent or unavailable. Offline functionality has become a crucial aspect of an app’s user experience, particularly for web and mobile JavaScript applications. In this article, we’ll delve into the world of offline-first development and explore how to build an anonymous chat app with offline capabilities using Create React App, RxDB, and PouchDB.
The Building Blocks of Offline Functionality
To make an application work without an internet connection, two essential components are required: local storage and continuous synchronization with a remote data source. Progressive Web Apps (PWAs) and Service Workers can store application files locally, while databases like PouchDB provide a means to store data locally and sync it automatically with a remote CouchDB database.
Building an Anonymous Chat App with Offline Capabilities
Using Create React App, we’ll generate a PWA with React and RxDB, a reactive, client-side, and offline-first database that syncs with a server-side CouchDB database. To get started, ensure you have Node version 6 or higher installed, as well as a modern browser that supports IndexedDB.
Setting Up the React App
First, install Create React App and create a new app. Then, install the necessary dependencies, including concurrently, moment, pouchdb-adapter-http, pouchdb-adapter-idb, pouchdb-server, react-toastify, rxdb, and rxjs. Next, edit the start script in the package.json file to execute the PouchDB server simultaneously with the application.
Configuring the Local Database
Create a schema for the app database using the JSON Schema standard. In this case, we’ll define a collection named “messages” with two properties: id and message. Then, configure the local database by importing the necessary modules, enabling debugging, and declaring constants for the remote database URL and local database name.
Building the App
Integrate the createDatabase method into the React app, adding imports for the notification component and moment library. In componentDidMount, call the createDatabase method and subscribe to a query that returns all messages sorted by id. Render the messages in a simple list, and add functionality to handle new messages and text box changes.
Testing the App
Execute npm start and navigate to http://localhost:3000. Add some messages, and notice the crown in the title indicating the leader tab. Open another tab, close the first one, and observe how the crown is transferred to the new tab. Thanks to RxDB’s reactive nature, the database state is broadcasted in real-time, reflecting changes in one tab automatically in another.
Going Offline
Build the application using create-react-app, and serve it with a service worker and manifest. Test the app in offline mode by disconnecting from the network or using the Offline option in Chrome’s Developer Tools. You should still be able to insert messages, and after reconnecting, observe the replication events and updated database state.
Conclusion
RxDB offers many more features, such as encryption, middleware hooks, and atomic update operations. This application can be extended by implementing editing and deleting operations or synchronizing data with a CouchDB server or IBM Cloudant database. By following this tutorial, you’ve unlocked the power of offline functionality in modern apps, providing a seamless user experience even in the absence of internet connectivity.