select刷新后，保持选定状态，Cookies存储select选定状态信息

    //cookies存储select选定值，防止刷新后没了
    window.onload = function () {
    var cooki = document.cookie;
    if (cooki != "") {
    cooki = "{\"" + cooki + "\"}";
    cooki = cooki.replace(/\s*/g, "").replace(/=/g, '":"').replace(/;/g, '","');
    var json = eval("(" + cooki + ")"); //将coolies转成json对象
    document.getElementById("pselect").options[json.selIndex].selected = true;//保持原来的选项
    }else
    save();
    } 

    function selectP(){
        var options=$("#pselect option:selected");
        var selectP=options.val();
        selectIndex = document.getElementById("pselect").selectedIndex;
        document.cookie = 'selIndex =' + selectIndex;//保存在cookie中，键名为selIndex 

        //alert(p);
        $.ajax(
                {
                   type:"post",
                   url:"<%=basePath%>servlet/UserServlet",
                   data:"oper=6&selectP=" + selectP,
                   success:function(data) {
                       //alert(data);

                         location.reload();

                   }
                });
    }