Traversing/API/jQuery - Sample Code
eq(index)
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<script src="/jquery/js/jquery.js"></script>
<script>
$(document).ready(function(){
$("div").eq(2).addClass("red");
});
</script>
<style>
div { width:60px; height:60px; margin:10px; float:left;
border:2px solid blue; }
.red { background:red; }
</style>
</head>
<body>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
<div></div>
</body>
</html>
[実行結果]