怎样删除一个select里的所有options

Question

for (i=0;i<select.length;i++)
select.options[i]=null;

Answer 1

for (i=0;i<select.length;i++)
select.options[0]=null;

Answer 2

<SCRIPT language=javascript>
function del(selectObjectId){
  var selectObject = document.getElementById(selectObjectId);
  selectObject.innerHTML = "";
}
</SCRIPT><hr>
<select name="select" id="select">
<option >dddddddddddddd</option>
<option>ddddddddd</option>
</select>
<input type="button" value="del" onclick="del('select')">

Answer 3

<SCRIPT language=javascript>
    function del()
    {
        select.remove(0);
    }
</SCRIPT>
<select name="select" id="select">
<option>aaaaa</option>
<option>bbbbb</option>
</select>
<input type="button" value="del" onclick="del()">

Answer 4

while(selectName.options.length>0)
{
    selectName.options.remove(0);
}