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
x
35
35
1
<html>2
<head>3
<title>Prototype examples</title>4
<script type = "text/javascript" src = "/javascript/prototype.js"></script>5
6
<script>7
function isDescendant() {8
var father = $('father');9
var kid = $('kid');10
11
// This is correct relationship and will be printed12
if( kid.descendantOf(father) ) {13
alert( "Kid is descendant of father" );14
}15
16
// This is wrong relationship and will not be printed17
if( father.descendantOf(kid) ) {18
alert( "Father is descendant of kid" );19
}20
}21
</script>22
</head>23
24
<body>25
<p>Click isDescendant button to see the result.</p>26
<div id = "grandfather">27
<div id = "father">28
<div id = "kid"></div>29
</div>30
</div>31
<br />32
33
<input type = "button" value = "isDescendant" onclick = "isDescendant();"/>34
</body>35
</html>返回到：Prototype – 元素对象
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作者：terry，如若转载，请注明出处：https://www.web176.com/prototype_api/9129.html
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