施用js验证年龄是否有18岁

使用js验证年龄是否有18岁
 <div class="renzhenglx_div">
                            <div class="renzheng_left_div" style="line-height: 20px">
                                生日：</div>
                            <div class="renzheng_right_div">
                                <select name="Date_Year" id="Date_Year" class="select_b_div" style="width: auto;">
                                </select>&nbsp;年&nbsp;&nbsp;
                                <select name="birthday_m" id="birthday_m" class="select_b_div" style="width: auto;">
                                </select>&nbsp;月&nbsp;&nbsp;
                                <select name="birthday_d"" id="birthday_d" class="select_b_div" style="width: auto;">
                                </select>&nbsp;日
                            </div>
                        </div>
------解决方案--------------------

 var date = new Date();

 var sYear = $("#Date_Year").val();

 var sMonth = $("#birthday_m").val();

 var sDay = $("#birthday_d").val();

 var dYear = date.getFullYear();

 var dMonth = date.getMonth()+1;

 var dDay = date.getDate();



 if((Number(dDay)-Number(sDay))<0)

 {

     dMonth -= 1;

 }

 if((Number(dMonth)-Number(sMonth))<0)

 {

     dYear -= 1;

 }

 if((Number(dYear)-Number(sYear))>=18)

 {

     alert("已满18岁");

  }

 else

 {

      alert("未满18岁");

  }