Detect which form input has focus using JavaScript or jQuery

Question

How do you detect which form input has focus using JavaScript or jQuery?

From within a function I want to be able to determine which form input has focus. I\'d like

Answer 1

If all you want to do is change the CSS for a particular form field when it gets focus, you could use the CSS ":focus" selector. For compatibility with IE6 which doesn't support this, you could use the IE7 library.