class method Event.findElement
Event.findElement(event[, expression]) → ElementReturns the first DOM element that matches a given CSS selector —
starting with the element on which the event occurred, then moving up
its ancestor chain. If expression is not given, the element which fired
the event is returned.
If no matching element is found, undefined is returned.
Example
Here's a simple example that lets you click everywhere on the page and hides the closest-fitting paragraph around your click (if any).
document.observe('click', function(event) {
  var element = event.findElement('p');
  if (element)
    $(element).hide();
});This method can be called either as an instance method or as a generic method. If calling as a generic, pass the instance in as the first argument.