选择了选项以后在文本框中就会显示相应的内容，用JS怎么实现？谢谢各位！
<form id="channel" name="channel" method="post" action="">
<table width="600" border="0" align="center" cellpadding="0" cellspacing="0">
<tr>
<td width="177" valign="top"><input name="channelname" type="text" id="channelname" /></td>
<td width="66" valign="top"><input name="add_chanel" type="submit" id="add_chanel" value="添加>>" /></td>
<td width="357" rowspan="3" valign="top"><select name="select" size="5">
<option value="1">选项1</option>
<option value="2">选项2</option>
<option value="3">选项3</option>
<option value="4">选项4</option>
<option value="5">选项5</option>
<option value="6">选项6</option>
</select>
</td>
</tr>
<tr>
<td valign="top"> </td>
<td valign="top"><input name="del_channel" type="submit" id="del_channel" value="删除<<" /></td>
</tr>
<tr>
<td valign="top"> </td>
<td valign="top"><input name="modi_channel" type="submit" id="modi_channel" value="修 改" /></td>
</tr>
</table>
</form>
