Synchronize text area in html

I am creating a simple web application in which whatever the client types on textarea field also appears on the server side textarea field at the same time.

The solution that i thought for this problem ..

I created a common file so that whatever user types on textarea in client gets saved in the file and the server side reads from the text-file at the same time.

But sadly i am not able to code it..Because of the problems i am facing in this ..

Everytime i save a file the cursor in the textarea gets to the beginning of the line which i dont want to happen...?

In order to save the data into text file i need to click on submit button ...Auto submit which i tried from this example http://ift.tt/1Eu6dH2 is not working ....

Can somebody help me to tackle this problem ?? Any help would be highly appreciated ...