innerText and innerHTML

//-----------innerHTML-----------------
<table> 
<tr> 
<td id="contants">aaaaaa 
<input type="button" onclick="a()" value="点击"> 
</td> 
</tr> 
</table> 
<script>... 
function a() 
...{ 
contants.innerHTML="<font style="font-size: 11pt">abc</font>" ; 
} 
</script> 

//------------------innerText--------------

<div id="clock">这是一个层</div> 
<script language="javascript">... 
function test() 
...{ 
var timevalue=new Date() 
document.all.clock.innerText=timevalue; 
} 
</script> 
<input type="button" value="设置" onclick="test()"> 
<input type="button" value="获取" Onclick="alert(clock.innerText)">

//DropDownList 添加客户端事件

<asp:DropDownList ID="DropDownList1" runat="server" onchange ="aa(this.options[this.selectedIndex].innerText)">
            <asp:ListItem>11</asp:ListItem>
            <asp:ListItem>22</asp:ListItem>
        </asp:DropDownList></div>

//生成的页面代码

</div>

    <div>
        <select name="DropDownList1" id="DropDownList1" onchange="aa(this.options[this.selectedIndex].innerText)">
 <option value="11">11</option>
 <option value="22">22</option>

</select></div>