有说明的下拉菜单

下面为效果显示

脚本说明:
把如下代码加入<body>区域中：
<form name="a294" >
<select name="a969" size="1" style="background-color:#FFFFD7" onChange="displaydesc(document.a294.a969.selectedIndex)">
<option selected value="http://7stk.com">网页特效代码</option>
<option value="http://163.com">网易</option>
<option value="http://sohu.com">搜狐</option>
<option value="http://the9.com">第九城市</option>
</select>
 <input type="button" value="Go" 
onClick="location=document.a294.a969.options[document.a294.a969.selectedIndex].value"><br>
<span id="descriptions" align="left" style="font:italic 13px Arial">
</span>
</form>

function displaydesc(which){
if (document.all)
descriptions.innerHTML=textdisplay[which]
else if (document.getElementById)
document.getElementById("descriptions").innerHTML=textdisplay[which]
}

displaydesc(document.a294.a969.selectedIndex)

document.a294.a969.options[0].selected=true

</script>