javascript中怎样添加下拉列表框的option到指定位置
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下拉列表框中数据是已经绑定了的 我现在要用javascript添加一项到最前面（变成第一项）像下面一样
options.add(new Option("全部", ""));
请问如何实现？
function tianjia()
newopt=document.createElement("option");
newopt.text="0";
newopt.value="00";
document.getElementById("a").options.add(newopt,0);
</script>
<select id="a">
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
</select>
<input type="button" onclick="tianjia()">本回答被提问者采纳 参考技术B <body>
<select id='select'>
<option>1</option>
<option>2</option>
<option>3</option>
<option>4</option>
</select>
</body>
<script>
var ele = document.getElementById('select');
var newOption = document.createElement('option');
var newSelect = document.createElement('select');
var optionArr=new Array();
var str='', num=0;
for (var i=0; i < ele.childNodes.length;i++)
if (ele.childNodes[i].innerhtml)
optionArr[num]=ele.childNodes[i];
num++;
newOption.innerHTML='0';
optionArr.reverse().push(newOption)
optionArr.reverse();
for (var i=0; i<optionArr.length; i++)
newSelect.appendChild(optionArr[i]);
newSelect.firstChild.selected=true;
ele.parentNode.replaceChild(newSelect,ele);
</script> 参考技术C <select name="select"id="select" style="width:150px;"onChange="if(this.value!=''&&this.value!='#')window.open(this.value);this.selectedIndex=0;">
<option>www</option> 参考技术D 用jQuery吧，下载个jquery1.4.0.1.js，用$(id).prepend(option); 第5个回答 2015-08-12 insert insertBefore
excel怎样添加的选项卡中含有下拉列表
1 <customUI 2 xmlns="http://schemas.microsoft.com/office/2006/01/customui"> 3 <ribbon startFromScratch="false"> 4 <tabs> 5 <tab id="myxxk" 6 insertBeforeMso="TabHome" 7 label="我的选项卡"> 8 <group id="cxgroup" 9 label="查询"> 10 <box id="rxbox1" 11 boxStyle="vertical"> 12 <box id="rxbox11" 13 boxStyle="horizontal"> 14 <comboBox 15 id="ks_n" 16 label="开始日期：" 17 onChange="ksn_Click" 18 getItemCount="nCount" 19 getItemID="nID" 20 getItemLabel="nLabel" 21 getText="nMoren"> 22 </comboBox> 23 <comboBox 24 id="ks_y" 25 sizeString="9999" 26 onChange="ksy_Click" 27 getItemCount="yCount" 28 getItemID="yID" 29 getItemLabel="yLabel" 30 getText="yMoren"> 31 </comboBox> 32 </box> 33 <box id="rxbox21" 34 boxStyle="horizontal"> 35 <comboBox 36 id="js_n" 37 label="结束日期：" 38 onChange="jsn_Click" 39 getItemCount="nCount" 40 getItemID="nID" 41 getItemLabel="nLabel" 42 getText="nMoren"> 43 </comboBox> 44 <comboBox 45 id="js_y" 46 sizeString="9999" 47 onChange="jsy_Click" 48 getItemCount="yCount" 49 getItemID="yID" 50 getItemLabel="yLabel" 51 getText="yMoren"> 52 </comboBox> 53 </box> 54 </box> 55 <button id="chaxun" 56 image="chaxun" 57 label=" 开始查询 
" 58 size="large" 59 onAction="chaxun_click"/> 60 </group> 61 </tab> 62 </tabs> 63 </ribbon> 64 </customUI>
1 \'生成年份下拉框选项文本 2 Public ksrq As Date, jsrq As Date 3 Sub nCount(control As IRibbonControl, ByRef returnedVal) 4 returnedVal = 16 5 End Sub 6 Sub nID(control As IRibbonControl, index As Integer, ByRef id) 7 id = control.id & index 8 End Sub 9 Sub nLabel(control As IRibbonControl, index As Integer, ByRef returnedVal) 10 returnedVal = 2000 + index & "年" 11 End Sub 12 13 \'生成月份下拉框选项文本 14 Sub yCount(control As IRibbonControl, ByRef returnedVal) 15 returnedVal = 12 16 End Sub 17 Sub yID(control As IRibbonControl, index As Integer, ByRef id) 18 id = control.id & index 19 End Sub 20 Sub yLabel(control As IRibbonControl, index As Integer, ByRef returnedVal) 21 returnedVal = index + 1 & "月" 22 End Sub 23 24 25 \'设置默认值 26 Sub nMoren(control As IRibbonControl, ByRef returnedVal) 27 returnedVal = IIf(Left(control.id, 1) = "k", "2010年", "2015年") 28 End Sub 29 Sub yMoren(control As IRibbonControl, ByRef returnedVal) 30 returnedVal = IIf(Left(control.id, 1) = "k", "1月", "12月") 31 End Sub 32 33 34 \'选择年月，保存到变量 35 Sub ksn_Click(control As IRibbonControl, text As String) 36 ksrq = DateSerial(Val(Left(text, 4)), Month(ksrq), 1) 37 End Sub 38 Sub ksy_Click(control As IRibbonControl, text As String) 39 ksrq = DateSerial(Year(ksrq), Val(LeftB(text, 2)), 1) 40 End Sub 41 Sub jsn_Click(control As IRibbonControl, text As String) 42 jsrq = DateSerial(Val(Left(text, 4)), Month(jsrq) + 1, 0) 43 End Sub 44 Sub jsy_Click(control As IRibbonControl, text As String) 45 jsrq = DateSerial(Year(jsrq), Val(LeftB(text, 2)) + 1, 0) 46 End Sub 47 48 49 \'点击查询按钮 50 Sub chaxun_click(control As IRibbonControl) 51 MsgBox "开始日期：" & Format(ksrq, "yyyy-mm-dd") & Chr(13) _ 52 & "结束日期：" & Format(jsrq, "yyyy-mm-dd") 53 End Sub
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