<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title></title>
    <script src="Scripts/jquery-1.4.1.js" type="text/javascript"></script>
    <script type="text/javascript">
        $(function () {
            $("#btn1").click(function () {
                $("#div1 input:checkbox").attr("checked", true);
                //$("#div1 :checkbox").attr("checked", true);//效果同上,中间要有空格
            });
        });
        $(function () {
            $("#btn2").click(function () {
                $("#div1 input:checkbox").attr("checked", false);
                //$("#div1 :checkbox").attr("checked", false);//效果同上,中间要有空格
            });
        });
        $(function () {
            $("#btn3").click(function () {
                $("#div1 input:checkbox").each(function () { 
                $(this).attr("checked",!$(this).attr("checked"));
                });
                //$("#div1 :checkbox").attr("checked", true);//效果同上,中间要有空格
            });
        });
    </script>
</head>
<body>
    <div id="div1">
        <input type="checkbox" value="lanqiu" />篮球<br />
        <input type="checkbox" value="zuqiu" />足球<br />
        <input type="checkbox" value="paiqiu" />排球<br />
        <input type="button" id="btn1" value="全选" />
        <input type="button" id="btn2" value="不选" />
        <input type="button" id="btn3" value="反选" />
    </div>
</body>
</html>