Ctrl Alt Del: Learning to Love Legacy Code Dylan Beattie

The world runs on legacy code. For every greenfield progressive web app with 100 test coverage, there are literally hundreds of archaic lineofbusiness applications running in production systems with no tests, no documentation, built using outofdate tools, languages and platforms. Its the code developers love to hate: its not exciting, its not shiny, and it wont look good on your CV but the world runs on legacy code, and, as developers, if were going to work on anything that actually matters, were going to end up dealing with legacy. To work effectively with this kind of system, we need to answer some fundamental questions: why was it built this way in the first place What s happened over the years it s been running in production And, most importantly, how can we develop our understanding of legacy codebases to the point where we re confident that we can add features, fix bugs and improve performance without making things worse Dylan worked on the web application stack at S