How to make any Web PAge Editable

hi ,there how are you all ?
so today i'm going to show you some funny script, when i was reading a book i found this java script .

javascript:document.body.contentEditable='true'; document.designMode='on'; void 0

try this script,visit any web site and past this script on url (where you type any website's name.)the whole web page can be editable on your browser ! you can delete any content of the page and past anything on the page !

so basically what's happening here  , when you past this script on the page the page suddenly go offline and make it editable for user.. this kind of function is also available in opera which is having this inbuilt feature  .

so enjoy this script. See the Example--------------