【ul】
<!DOCTYPE html>
<html>
<head>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js">
</script>
<script>
$(function() {
var item2 = document.getElementById("item2");
document.writeln($("li").index(item2));
});
</script>
</head>
<body>
<ul>
<li id="item0">A</li>
<li id="item1">B</li>
<li id="item2">java 2s.com</li>
<li id="item3">D</li>
<li id="item4">E</li>
<li id="item5">F</li>
</ul>
</body>
</html>
