First, create the basic code that displays a simple base map and visualizes GeoJSON from a file. To do this, run the generator. Because we are to start simple, you should have answered "GeoJSON from a file" to the generator's question "What kind of data will you visualize on top of the Base map?".
After finishing scaffolding the base code, you can access your app at http://localhost:8080. The
webpack-dev-server listens for any changes that you make to the source code in the file system and automatically refreshes the web page in the browser according to your changes in the code.
Run this web app and check it in your browser. You should see an empty map with the Authentication form. After successful authentication, you will see a base map that points to the center of Berlin: