May I recommend a clean, blank, text-editor is used for every new concept introduced?

I watched the entire series, and thanks to Guil.

I would like to add, since I saw a few comments saying it was a bit hard to follow (I attribute this mostly to mentally mapping the DOM traversal being a bit abstract), however, I believe adding code on-top of existing code i.e. show/hiding the <li> list, adding a new <li> element, adding event listener for the <li> hover .toUpperCase(), removing an element, moving up/down elements ETC..... only further complicated matters and made it more difficult to understand.

I believe having just shown the adding method, writing the code etc... and showing step by step THEN when moving to the NEXT concept, erase all that code and just introduce the next concept with fresh code.

There were re-used variables ontop of the file being reused multiple sections later when most of us probably forget what they were, and an entire page of code being copied & pasted in pre-existing event handlers and being shifted around with blocks of text all around. I'm not trying to be picky but I really feel something as subtle as this will make it much harder for newer programmers to learn this stuff.

Thank you.