Find one thing you know the code does, and trace those actions backward, starting at the end
Say, for example, you know that the code you're viewing ultimately creates a file with a list of movie titles. Figure out where in the code - the specific, few lines - it generates that file.
Then, move one step backward and figure out how it places the info in the file.
Them, move another step backward and figure out where the info came from
how the body of code is organized(where variables are defined, where different types of functions are located, etc)
the person's style of coding
how the person who wrote the code thinks and problem solves
[ a big file of code that doesn't really mean much at all to you ]
you'll now be looking at:
[ still a big file of code, but where you now understank a few specific sections ]
using "chains of actions" to gradually understand a never-before-seen piece of code
Rinse and repeat
Repeat that process multiple times, and you'll rapidly increase your understanding of more and more pieces of the overall codebase
The reason that works well is that, in all cases, a body of code is designed to tackle one or more complex problems. So you'll always have those "chains of actions" throughout
And the more you can gain an understanding of how different parts of the code are connected, the more you'll develop an understanding of the entire codebase
The more good code you see, the easier it becomes to read and understand all code, and the faster you cando so
The more you watch to expert examples, the better you can become. The less exposure you have to experts or result of expert workm the less likely you are to develope expert skills
