This method checks if element is a descendant of ancestor.
As Element.descendantOf internally applies $() to ancestor, it accepts indifferently an element or an element's id as its second argument.
Syntax:
element.descendantOf(ancestor);
Return Value:
If it finds that element is a decendant of an ancestor then it returns true otherwise false
Example:
<html>
<head>
<title>Prototype examples</title>
<script type="text/javascript"
src="/javascript/prototype.js">
</script>
<script>
function isDescendant(){
var father = $('father');
var kid = $('kid');
// This is correct relationship and will be printed
if( kid.descendantOf(father) ){
alert( "Kid is descendant of father" );
}
// This is wrong relationship and will not be printed
if( father.descendantOf(kid) ){
alert( "Father is descendant of kid" );
}
}
</script>
</head>
<body>
<p>Click isDescendant button to see the result.</p>
<div id="grandfather">
<div id="father">
<div id="kid"></div>
</div>
</div>
<br />
<input type="button" value="isDescendant"
onclick="isDescendant();"/>
</body>
</html>