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<!--
This demonstrates the effectiveness a method for testing for visibility elements on various conditions.
-->
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<title>Visibility test</title>
<style type="text/css" media="screen">
span {
display:block;
width:30px;
height:20px;
background-color:blue;
}
</style>
<script type="text/javascript" charset="utf-8">
window.addEventListener("load", checkDivsForVisibility, false);
function checkDivsForVisibility() {
var divs = document.getElementsByTagName("span");
for (var i = 0; i < divs.length; i++) {
console.log(divs[i].id, isVisible(divs[i]));
}
}
/*
* Determines whether this element is on screen and visible.
* See this for some helpful discussion:
* http://stackoverflow.com/questions/704758/how-to-check-if-an-element-is-really-visible-with-javascript
*/
function isVisible(element) {
var boundingRect = element.getBoundingClientRect();
var elementFromPoint = document.elementFromPoint(boundingRect.left, boundingRect.top);
return elementFromPoint == element;
}
</script>
</head>
<body>
<span id="div1true"></span>
<span id="div2false" style="visibility:hidden"></span>
<span id="div3false" style="display:none"></span>
<span id="div4false" style="position:absolute;top:2000px"></span>
<div style="visibility:hidden">
<span id="div5false"></span>
</div>
<div style="display:none">
<span id="div6false"></span>
</div>
<div style="opacity:0">
<span id="div7true" style="opacity:0"></span>
</div>
</html>
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