One of the most powerful features of Ionic is that the majority of your app development can happen right in a browser on your desktop. With full access to traditional web development tools (Chrome/Safari/Firefox dev tools), you can write code then test/debug it quickly without having to recompile or deploy to a simulator or device.
To do so, run
ionic serve from the command line in the project's directory:
[INFO] Development server running!
Use Ctrl+C to quit this process
[INFO] Browser window opened to http://localhost:8100!
ionic serve running, continue developing your app. As you save changes, the app reloads with those changes applied.