Question : how to determine style.display value

I've got a problem. I have a style and html as follows:

.hideMe {display:none;}
:
<tr id="myId" onclick="doThis('myId') class=hideMe> .... </tr>

My doThis() function is supposed to determine the current state of the display attribute and switch it back and forth. The problem is, the elements display attribute value is initially empty, so I can't tell whether it is "none" or whatever the 1st time.

How can I figure this out?

Answer : how to determine style.display value

see if the class equals "hideMe"

function doThis( el )
{
   el =document.getElementById(el);
  if( el )
  {
     el.className = el.className.indexOf('hideMe') ==-1 ? el.className + " hideMe" : el.className.replace("hideMe","");
  }
}