javascript - How to get location of the element after it was clicked?

I have HTML element(span) the changes it's location.When I click HTML element(span) I need to get the HTML element(span)'s location.

Here is html:

                                                                        onmouseover="HoverButton('btn4', null)" 
                                                                        onmouseout="LeaveButton('btn4', '')" 
                                                                        onclick="OpenFlyout('cell4', 4, event)">
   measure 
    
  

Here is onclick event:

  function OpenFlyout(xpos, tbItemIndex, e)
  {

  }

How can I get HTML element(span) location in OpenFlyout function?