Making A Collaborative Notepad

[Gunderak]

Im trying to make a notepad that whoever has it open whenever they write in it it will appear on your screen.
vise versa.
here is what i have so far, is there any form of ontextchanged or anything?

Sorry for it being a file and not php.
incapsula keeps being annoying and not letting me post it.
it seems when i post my script if i use onTimeout(); or function onTimeout(){ it takes me to the incapsula error page.