title: textarea empty should show disabled button
body: <p>I am having a textarea and a button. There are two classes buttonEnabled and buttonDisabled. I want to apply buttonEnabled only when there is some text in the textarea. So if user is typing in a textarea then button looks enabled and when he clears all the text either by selecting and cutting it or by backspace. I want my button to look disabled. Also i want to do this only with javascript and for some reason dont want to use jQuery.</p>