Implementing a resizable textarea?

Question

How does Stackoverflow implement the resizable textarea?

Is that something they rolled themselves or is it a publicly available component that I can easily attach to

Answer 1

At first I believed it was a built-in feature of the Wysiwym Markdown editor, but Shog9 is correct: it's not baked-in at all, but is courtesy of the jQuery plugin TextAreaResizer (I was lead astray by the browser was using to check on the editor demo because Google Chrome itself adds the expandable functionality on textareas—much like the Safari browser does).