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> 年  
<select name="birthday_m" id="birthday_m" class="select_b_div" style="width: auto;">
</select> 月  
<select name="birthday_d"" id="birthday_d" class="select_b_div" style="width: auto;">
</select> 日
</div>
</div>
[解决办法]

 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");
  }