App.js

In and React Native , App.js is typically the "root" component of your application. While index.js usually handles the technicality of mounting the app to the browser or device, App.js is where your actual visual structure begins.

For backend developers using (often with the Express framework), app.js is the traditional name for the main server file. app.js

It acts as the parent to all other components. If you have a navigation bar, a footer, and a main content area, they are usually imported and organized here. In and React Native , App