使用jQuery很容易...

It's easy with jQuery...

$("div:visible")

但是如果你想上老学...

But if you want to be old school...

var divs = document.getElementsByTagName("DIV");
var elems = [];

for(var i = 0; i < divs.length; i++) {
  var div = divs[i];
  var vis = div.style.visibility;

  if(vis == 'block' || vis == 'inline')
    elems.push(div);
}