I do most of my work in browser tabs, but often need a "scratch pad" to paste or type things in, like snippets of code or a short todo list. And I use TextEdit on my Mac, but I'd prefer a browser tab so this is wonderful.
Four requests, from most to least important:
1) Let me choose the font and font size? For code snippets, I really want monospace. And make sure the preference persists
2) Keep current contents in local storage, so it survives a browser restart? (Or maybe you do already?)
3) Having tabs feels redundant with my browser tabs -- I'd rather get rid of the extra bar at the top and just have a 100% clean typing space, with just the (wonderfully unobtrusive) menu bar. (I understand their utility in a PWA though, maybe a menu option to toggle the tab bar? Also full screen mode to hide the menu bar for a pure editing experience?)
4) Get a proper domain name. :) So I can start typing "note" in my address bar and it will autocomplete. Surely "notepadjs" is available for some TLD? Or "notepadx" (for cross-platform) or "notepage" (for webpage) or similar?
But this is a great idea. I'm surprised I've never come across something like it before, it seems so obvious in hindsight. I love it.