Prototype - previousSiblings() 方法
此方法收集元素的所有先前同级元素，并将它们作为扩展元素数组返回。
如果两个元素具有相同的父元素，则它们为同级元素。例如，head 和 body 元素是同级元素(它们的父元素是 html 元素)。先前同级元素只是文档中位于元素之前的元素。
语法
element.previousSiblings();
返回值
返回 HTML 元素数组。
示例
<html>
<head>
<title>Prototype examples</title>
<script type = "text/javascript" src = "/javascript/prototype.js"></script>
<script>
function showResult() {
var arr = $('ida-red').previousSiblings();
arr.each(function(node) {
alert(node.nodeName + ': ' + node.innerHTML);
});
}
</script>
</head>
<body>
<p>单击按钮查看结果。</p>
<ul id = "fruits">
<li id = "apples">
<h3 id = "title">Apples</h3>
<ul id = "list-of-apples">
<li id = "golden-delicious">Golden Delicious</li>
<li id = "mutsu">Mutsu</li>
<li id = "mcintosh" class = "yummy">McIntosh</li>
<li id = "ida-red" class = "yummy">Ida Red</li>
</ul>
<p id = "saying">An apple a day keeps the doctor away.</p>
</li>
</ul>
<br />
<input type = "button" value = "Show Result" onclick = "showResult();"/>
</body>
</html>
prototype_element_object.html
