javascript中如使用onchange获得select的name及下标?

<select name='stuname' onChange="cleartext();">
<select name='stuname' onChange="cleartext();">
<select name='stuname' onChange="cleartext();">
<select name='stuname' onChange="cleartext();">

将select定义了成一维数组,问改变当前其一个select的值,如何获取stuname数组的下标?
即如何获得获得onchange了当前select对象name在数组的下标或是行号?select定义在表格中

楼主,看代码吧.

<select name='stuname' onChange="cleartext(this);">
<option value="2">2</option>
<option value="1">1</option>
</select>
<select name='stuname' onChange="cleartext(this);">
<option value="2">2</option>
<option value="1">1</option>
</select>
<select name='stuname' onChange="cleartext(this);">
<option value="2">2</option>
<option value="1">1</option>
</select>
<select name='stuname' onChange="cleartext(this);">
<option value="2">2</option>
<option value="1">1</option>
</select>
<script>
function cleartext(){
var tt = document.getElementsByName("stuname");