点击input框时，在input框下边展示一个div

    
//此处在div中的ul是一个ztree树
var html='<div id="'+btnName+'DropDown" style="display: none;position:absolute; height:200px; min-150px; background-color:white;border:1px solid;overflow-y:auto;overflow-x:auto;z-index: 999999">'+
        '<ul id="'+btnName+'Tree" class="ztree"></ul>'+
        '</div>'
    $("body").append(html);    



    //站点文本框点击事件
    $btn.click(function () {
        var stationObj = $btn;
        var stationOffset = $btn.offset();
        $("#"+btnName+"DropDown").css({left:stationOffset.left + "px", top:stationOffset.top + stationObj.outerHeight() + "px"}).slideDown("fast");
    });



　　//站点选择失去焦点
    $("body").bind("mousedown",
        function(event){
            if (!(event.target.id == btnName || event.target.id == btnName+"DropDown" || $(event.target).parents("#"+btnName+"DropDown").length>0)) {
                $("#"+btnName+"DropDown").fadeOut("fast");
            }
        }
    );