There's a category of articles out there nowadays that do "$library in $num lines of code", reducing popular libraries or frameworks down to their core - filtering out all the edge cases, so to speak. I've seen them for Angular, React, Redux, etc. I think that a lot of frameworks and libraries would do good to have a "core" codebase somewhere, something pure but unoptimized and without edge cases that are easily digestable, that explain the core idea of it.
I've read blog posts that go through the entire redux javascript library line by line, or review an entire chunk of React.
Even just yesterday here on HN was a submission that just contained shaders from Wolfenstein.