1.html代码如下：
<html><head></head><body><form name="form1" id="form1">Select your favorite fruit:<select id="mySelect" name="mySelect"><option value="11">Apple</option><option value="22" >Orange</option><option value="33">Pineapple</option><option value="44">Banana</option></select><br /><br /><input type="button" οnclick="getIndex()"value="Alert index of selected option"></form></body></html>
2.javascript代码如下：
<script type="text/javascript">function getIndex(){//从document对象中，获取select标签var a=document.getElementById("mySelect");//select标签获取的值其实是一个数组--a.options[]; 然后，选定项的下标是--a.selectedIndexvar b=a.options[a.selectedIndex].value; alert(b); } </script>
