I want to ask a question that if there is any library or thing that allow desktop sharing from browser, i am not asking about screen-sharing (i.e a browser page through webrtc) i am asking about desktop sharing (like teamviewer) means other user can use your computer from his browser and the other person is getting whole screen of your computer not just a particular tab.
if your answer is it cannot be done because JS will loaded in a particular tab then can it be possible by using some small app that transfer screen data/video bytes to browser and then it sent to the other person.
I believe what you are looking for is : WebRTC
Following these links:
Firefox Extension (sample) : http://mozilla.github.io/webrtc-landing/
Add your *. to about:config -> getUserMedia screensharing allowed domains
Google Chrome extension (sample) : https://developer.chrome.com/extensions/samples#search
Open this in Run : Chrome.exe --enable-usermedia-screen-capturing
Other Reference : https://github.com/muaz-khan/WebRTC-Experiment