To start with, look at the "Crazy Hack 1" at the "Crazy Cool Javascript Hacks" page:
https://bhuvans.wordpress.com/2007/01/22/crazy-cool-javascript-hacks[
^].
Simple, isn't it? Only you can "turn it on" on your page yourself in first place.
Now, it says: "of course you cannot save it back". But of course you can make
your own page to do so. For example, you can serialize all the new content, send it back to the server side using Ajax and do whatever you want with it on the server side — this is ASP.NET.
—SA