返回到：Prototype – 元素对象
此方法检查元素是否是祖先的后代。
由于 Element.descendantOf 在内部将 $() 应用于祖先，它无差别地接受一个元素或一个元素的 id 作为它的第二个参数。
语法
element.descendantOf(ancestor);
返回值
如果它发现该元素是祖先的后代，则返回 true，否则返回 false。
例子
<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>返回到：Prototype – 元素对象
作者：terry，如若转载，请注明出处：https://www.web176.com/prototype_api/9129.html
