• An empty string ("")
• "hidden"
• "visible"

An element is visible when its style object's visibility property is either empty ("") or "visible". It is invisible when the property is "hidden".

When you initially place an element, its default visibility is an empty string (""). The following code segment renders two buttons and their onclick event handler:

<FORM>
<INPUT ID="button1" STYLE="position:relative; left:0;" TYPE="button" VALUE="Show Visibility of Other Button" onclick="handleClick()">
<INPUT ID="button2" STYLE="position:relative; left:150;" TYPE="button" VALUE="Show My Visibility" onclick="handleClick()">
</FORM>
<SCRIPT LANGUAGE="JavaScript">
<!--
function handleClick() {
  alert('visibility = "' + document.getElementById('button2').style.visibility + '"');
}
// -->
</SCRIPT>

Click the left button to find out the visibility value of the right button. It should show an empty string::

if (visibility == "")...

or

if (visibility != "hidden")...

This script does not work on Mac IE4.5.

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