<p>in javascript, when I receive a focus event, how can I work out which element has lost focus? I'm trying to avoid having to put an onblur event handler on all elements within my web page. </p>

@pbrodka: the target/srcElement property would refer to the element with focus for onfocus events
offhand I can't see a way to get this short of onblur, or if the set of objects you care about all have focus methods you could store a reference to that object instead. It's also possible event bubbling could get you out of jail
this all feels like a bit of a code smell though - perhaps you need to describe the problem in more detail