怎么用javascript來刪除選擇菜單里的所有內容(選項)

[colee]

怎么用javascript來刪除選擇菜單里的所有內容(選項),
如將<select name="selectname">
<option value="3">3</option>
<option value="4">4</option>
<option value="5">5</option>
</select>
變成<select name="selectname"></select>;
(其實目的是,我可以再重新為它添加選項.)

[lgchao]

selectname.options.length=0

[孟子E章]

<select name="selectname" onchange='this.innerHTML=""'>
<option value="3">3</option>
<option value="4">4</option>
<option value="5">5</option>
</select>

[fason]

精!innerHTML就可以把容器里面的html清除,试试用outerHTML,整个都没有了

[possible_Y]

<SELECT NAME="Cats" SIZE="1">
<OPTION VALUE="1">Calico
<OPTION VALUE="2">Tortie
<OPTION VALUE="3" SELECTED>Siamese
</SELECT>
<button onclick="removeAll()">Remove All</button>
<script language="JavaScript">
function removeAll(){
while(Cats.childNodes.length>0)
Cats.removeChild(Cats.childNodes(0));
}
</script>
<SELECT NAME="Cats1" SIZE="1">
<OPTION VALUE="1">Calico
<OPTION VALUE="2">Tortie
<OPTION VALUE="3" SELECTED>Siamese
</SELECT>
<button onclick="Cats1.length=0">Remove All</button>

[zhanghk]

while(selectid.options.length)
selectid.options[selectid.options.length -1 ] = null;