Hidden hiddens

When a hidden item is really hidden

HTML

<div id="someContainer" style="overflow:hidden; position:relative; height:26px; background-color: #ffffff;">
  <div class="item">A</div>
  <div class="item">B</div>
  <div class="item">C</div>
</div>
<pre id="output"></pre>

JavaScript

var i, top, container, output, height;

container = document.getElementById("someContainer");
output = document.getElementById("output");
height = container.offsetHeight;

output.innerText += "Height: " + height + "px\n";

for (i = 0; i < container.children.length; i++)
{
  top = container.children[i].offsetTop;
  output.innerText += "Top " + i + ": " + top + "px => visible=" + (top < height) + "\n";
}