i just came across an absolutely genius bookmarklet (that kinda isn't that because it's not JS but like works the same) that literally just spawns an editable full page textarea in a new browser tab and functions as a little scratchpad you can copy/paste from. it's like a single tiny line of code. i'm fucking obsessed. https://joonakeskitalo.github.io/2024/06/14/Useful-things/#temporary-pasteboard-in-browser