I am currently in the process of doing something similar: https://github.com/CarlMungazi/aprender-js https://github.com/CarlMungazi/aprender-js Once I'm done,

I am currently in the process of doing something similar: https://github.com/CarlMungazi/aprender-js https://github.com/CarlMungazi/aprender-js Once I'm done, I'm probably going to have a proper crack and either building my own tool or collating smaller libraries (and by small I mean they do one thing only and do it very well) into a toolkit I can build stuff very quickly with. I think the knowledge gained by building your own tool (CSS library, UI framework, state management library etc) seeps into any work you do with other tools or programming in general. It also depends on your aim. You will be more productive using whatever approach you spend time learning deeply.