Debugging

There are a few basic tools and techniques that can help you to debug applications.

Use Chrome DevTools to debug your client-side code.

To open DevTools on Windows and Linux, press Control-Shift-I in your Google Chrome browser. On Mac, press Option-Command-I.
To quickly find which line of code is failing, enable the Pause on all exceptions option before running your code.

To learn more about debugging JavaScript on Google Chrome, refer to the Google Chrome’s DevTools website.

Check out this video on how to troubleshoot your Aura components.

Video from VidYard

Disable Caching Setting During Development

Disable the secure and persistent browser caching setting during development in a sandbox or Developer Edition org to see the effect of any code changes without needing to empty the cache.
Log Messages

To help debug your client-side code, you can write output to the JavaScript console of a web browser using console.log() if your browser supports it..