<select name="year">
          <option>1980</option>
          <option>1981</option>
          <option>1982</option>
          <option>1983</option>
          <option>1984</option>
          <option>1985</option>
          <option>1986</option>
          <option>1987</option>
          <option>1988</option>
          <option>1989</option>
          <option>1990</option>
          <option>1991</option>
          <option>1992</option>
          <option>1993</option>
          <option>1994</option>
          <option>1995</option>
          <option>1996</option>
          <option>1997</option>
          <option>1998</option>
          <option>1999</option>
          <option>2000</option>
      </select>
      年　
      <select name="months">
        <option>1</option>
        <option>2</option>
        <option>3</option>
        <option>4</option>
        <option>5</option>
        <option>6</option>
        <option>7</option>
        <option>8</option>
        <option>9</option>
        <option>10</option>
        <option>11</option>
        <option>12</option>
      </select>
      月
      <select name="day">
        <option>1</option>
        <option>2</option>
        <option>3</option>
        <option>4</option>
        <option>5</option>
        <option>6</option>
        <option>7</option>
        <option>8</option>
        <option>9</option>
        <option>10</option>
        <option>11</option>
        <option>12</option>
        <option>13</option>
        <option>14</option>
        <option>15</option>
        <option>16</option>
        <option>17</option>
        <option>18</option>
        <option>19</option>
        <option>20</option>
        <option>21</option>
        <option>22</option>
        <option>23</option>
        <option>24</option>
        <option>25</option>
        <option>26</option>
        <option>27</option>
        <option>28</option>
        <option>29</option>
        <option>30</option>
        <option>31</option>
      </select>
 
做了一个年月日的选择生日菜单，希望去验证他的合法性，例如4 6 9 11月没有31号等 我查到一个获取select值的方法，但是就是做不出来 希望斑竹给看下 我还在想 先贴出来 谢
            var themonths=document.getElementByld(months);   //months是我月份select的name 天的select的name是day
            var theday=document.getElementByld(day);
            return day.value;return months.value;
            if (themonths=4 && theday=31)
               {
                alert('请输入正确的生日')
                return false
               }
我想定义两个变量 获取select的值给予这两个变量  然后让他们去做if  不知道哪里出岔子了。。。？！~~~

[ 本帖最后由 xiaozhumt 于 2011-3-8 15:32 编辑 ]

<script type="text/javascript">
  function form_validator(theform)
        {

            if (theform.Enterprise_Name.value=="")
               {
                alert('用户名不能为空...');
                theform.Enterprise_Name.focus();
                return false
               }
            if(theform.nc.value=="")
               {
               alert('昵称不能为空')
               theform.nc.focus();
               return false
               }
            if (theform.pwd.value=="")
            {
                alert("密码不能为空");
                theform.pwd.focus();
                return false;
            }
            if (theform.repwd.value=="")
              {
              alert('确认密码不能为空');
              theform.repwd.focus();
              return false
              }
            if (theform.pwd.value != document.luntan.repwd.value)
                {
                  alert('两次输入的密码不一致')
                  theform.pwd.focus();
                  return false
                }
                if(theform.email.value.indexOf('@')==-1 || theform.email.value.indexOf('.')< (theform.email.value.indexOf('@')))//indexOf()是检索 -1是在第一个字符开始检索 第一个字符为0
                {
                alert('请输入正确的email');
                theform.email.focus();
                return false
                 }
            if ((theform.introduction.value.length<5) || (theform.introduction.value.length>10000))
                {
                 alert('简介长度应大于5小于10000')
                 theform.introduction.focus();
                 return false
                 }
            if (theform.getElementByld('themonths').options=4)
                 {
                  alert('请输入正确的生日')
                  return false
                 }
                 return(true)
            if ((year%4==0&&year%100!=0)||year%400==0)
            {
            var two=28
            }
            else {var two =29}//这个var不能省略
            var themonths=parseInt(theform.months.value);
            switch themonths
            {
            case 2:if theform.day.value>two {alert('请输入正确的天数');theform.day.focus(); return false}break;
            case 4:if theform.day.value>30 {alert('请输入正确的天数');theform.day.focus();return false}break;
            }
            return true
            
        }
实现不了啊。。  斑竹你那个obj什么意思 怎么用？我这个应该也可以吧  ？这样做完  连我上面的方法都失效了。。

斑竹  你的这句话帮忙一下  实在不明白 var obj=function(id){return document.getElementById?document.getElementById(id):id};
我看了getElementById的说明 和你写的不一样啊  读不懂
语法：
　　obj= document . getElementById ( sID )
　　参数：
　　sID :　必选项。字符串(String)。
　　返回值：
　　obj:　对象(object)。
一中午了 就这个玩意卡着儿了

var year=parseInt(theform.year.value); //因为下面的if要涉及运算 所以去int类型 用parseInt
            if((year%4==0&&year%100!=0)||year%400==0)
                 {
                 var two=29;
                 }
             else
                {
                 var two=28;
                }
            var yue=parseInt(theform.months.value);
            switch (yue)
               {
                case 2:if(theform.day.value>two){alert('请输入正确的天数');theform.day.focus();return false;}break
                case 4:
                case 6:
                case 9:
                case 11:
                       if(theform.day.value>30){alert('请输入正确的天数');theform.day.focus();return false;}break
               }

搞定啦  总之谢谢斑竹   最后的问题出现在我用dreamweaer做select的时候  代码里面select没有value值  现在好啦  不过斑竹的function我不是很懂。。  还有用dreamweaer做select怎么样直接给value？一个一个打麻烦死了。。。知道的麻烦告诉下 谢谢  哈哈  好开心 做通了！~