I prefer to think of this as a clean slate, typing tool.
If you have something you want to type out on the spur of the moment, and don’t want to muck around with a word processor, then this is a neat trick.
Sometimes I just need to type garbage. Just to clear out my mind. Using editors to type such gibberish annoys me because it clutters my project workspace (I’m picky, I know).
So I do this. Since I live in the browser, I just open a new tab and type in the url tab.
data:text/html, <html contenteditable>
Voila, browser notepad.
Why it works?
source: Jose Jesus Perez Aguinaga