What’s the best way to tackle a complex codebase for the first time?

You don't really need to learn the entire codebase right away. Instead, start with the overall design concepts and focus on the parts that are relevant to your current task. A good initial step is to check out the README or the main function to get the lay of the land.

My approach usually involves a few structured steps: 1) Understand the core data models driving the main functionalities. 2) Play with the actual application to see how the data interacts on-screen. 3) Finally, pick one specific area to learn in-depth. If possible, document your findings as you go!

Yeah, trying to master everything at once isn't the way to go. You're likely to work on specific segments, so zero in on those areas and gradually expand your knowledge as you go.

When you know what part of the code you'll be working on, break it down into manageable sections. Having a grasp of the programming language and framework you're dealing with can speed up the process, but don't worry if it takes a bit longer to fully understand everything.

One of my favorite strategies is to start writing unit tests. It helps you get familiar with the code and its performance, making it easier to understand the functionality.