I have created one simple note taking application in jquery & php. Current functionality is like when user clicks save button it sends a ajax request with complete data to update it in db(mysql). All works well. But now I want to auto save only changed text while user typing. I don't want to send entire text to server again and again in text change event. It should send only text which has changed.

For Ex: This is saved text.

When user continues typing. This is saved text. Unsaved text..

It should be able to send only "Unsaved text.." to server to update in db.

How can i implement this in jquery & server side script.? Any Idea..?