如何根据下拉框选择的内容来和当前年份比较,自动获得一个值赋给一个隐藏表单?
在做用户注册页时,我想让用户自己选择是哪年哪月出生的,同时能根据他选择的年份自动计算他现在的岁数,然后把这个值赋给这个页的一个隐藏表单,对应数据表里的age字段,这个该如何实现呢?
字段结构:
Birth_Year 出生年份
Birth_Month 出生月份
age 年龄

...
<TR bgcolor= "#FFFFFF ">
<TD height= "25 "> 出生年月： </TD>
<TD height= "25 "> <label>
<select name= "Birth_Year " id= "Birth_Year ">
<option value= "1970 "> 1970 </option>
<option value= "1971 "> 1971 </option>
<option value= "1972 "> 1972 </option>
<option value= "1973 "> 1973 </option>
<option value= "1974 "> 1974 </option>
<option value= "1975 "> 1975 </option>
<option value= "1976 "> 1976 </option>
<option value= "1977 "> 1977 </option>
<option value= "1978 " selected> 1978 </option>
<option value= "1979 "> 1979 </option>
<option value= "1980 "> 1980 </option>
<option value= "1981 "> 1981 </option>
<option value= "1982 "> 1982 </option>
<option value= "1983 "> 1983 </option>
<option value= "1984 "> 1984 </option>
<option value= "1985 "> 1985 </option>
<option value= "1986 "> 1986 </option>
<option value= "1987 "> 1987 </option>
<option value= "1988 "> 1988 </option>
<option value= "1989 "> 1989 </option>
<option value= "1990 "> 1990 </option>
</select>
</label>
年
<label>
<select name= "Birth_Month " id= "Birth_Month ">

<option value= "1 "> 1 </option>
<option value= "2 "> 2 </option>
<option value= "3 "> 3 </option>
<option value= "4 "> 4 </option>
<option value= "5 "> 5 </option>
<option value= "6 "> 6 </option>
<option value= "7 "> 7 </option>
<option value= "8 "> 8 </option>
<option value= "9 "> 9 </option>
<option value= "10 "> 10 </option>
<option value= "11 "> 11 </option>
<option value= "12 "> 12 </option>
</select>
</label>
月 </TD>
</TR>
<TR bgcolor= "#f1f1f1 ">
<TD height= "25 " bgcolor= "#f1f1f1 "> </TD>
<TD height= "25 "> <input name= "age " type= "hidden " id= "age " size= "10 " maxlength= "4 "> </TD>
</TR>
...

[解决办法]
太麻烦了 我说个思路你自己试着写
首先定义
var Digital = new Date()
var year = Digital.getFullYear(); //取得4位 年份
var month= Digital.getMonth()+1; //取得月份
var sysdate = year + "- " + month;
然后
var obj = document.getElementById( "Birth_Year ");
var yr =obj.options[obj.selectedIndex].text; //取得你选择年的值

月份同理
var obj = document.getElementById( "Birth_Month ");
var mo =obj.options[obj.selectedIndex].text; //取得你选择月的值


再定义
var date = yr + "- " + mo；
连接起来var diff =date-sysdate;

<input type=hidden id = " " name= " "> //放到隐藏控件中