How do you clear the focus in javascript?

Answer: document.activeElement

To do what you want, use document.activeElement.blur()

If you need to support Firefox 2, you can also use this:

function onElementFocused(e)
{
    if (e && e.target)
        document.activeElement = e.target == document ? null : e.target;
} 

if (document.addEventListener) 
    document.addEventListener("focus", onElementFocused, true);