Make editor's textarea auto resize when height of text exceeds height of textarea

For example, if the textarea has a default height of, say, 10 lines, if my text has more than 10 lines a vertical scrollbar will appear. In that case, in order to be able to view my whole message, I need to manually resize the textarea and scroll the page to fit it into view.

What I am suggesting is for the text area to automatically recalculate its height, and fit it into view, if possible, according to height of the the lines of the text I am writing.

Sort of like how GitHub does it.