javascript操作select和option
    注意:Option中的O是要大写的,不然语法报错 
1.动态创建select 
      function createSelect(){ 
var mySelect = document.createElement("select");
          mySelect.id = "mySelect";  
          document.body.appendChild(mySelect);
      } 
2.添加选项option 
     function addOption(){ 
          //根据id查找对象,
           var obj=document.getElementById('mySelect'); 
           //添加一个选项
obj.add(new Option("文本","值"));    //这个只能在IE中有效
         obj.options.add(new Option("text","value")); //这个兼容IE与firefox
     } 
3.删除所有选项option 
     function removeAll(){
           var obj=document.getElementById('mySelect');
obj.options.length=0; 
     } 
4.删除一个选项option 
function removeOne(){
           var obj=document.getElementById('mySelect'); 
           //index,要删除选项的序号,这里取当前选中选项的序号 
var index=obj.selectedIndex;
obj.options.remove(index);
     } 
5.获得选项option的值 
var obj=document.getElementById('mySelect'); 
var index=obj.selectedIndex; //序号,取当前选中选项的序号 
var val = obj.options[index].value; 
6.获得选项option的文本 
var obj=document.getElementById('mySelect'); 
var index=obj.selectedIndex; //序号,取当前选中选项的序号 
var val = obj.options[index].text; 
7.修改选项option 
var obj=document.getElementById('mySelect'); 
var index=obj.selectedIndex; //序号,取当前选中选项的序号 
var val = obj.options[index]=new Option("新文本","新值"); 
8.删除select 
      function removeSelect(){
            var mySelect = document.getElementById("mySelect");
mySelect.parentNode.removeChild(mySelect);
     }   
整个实例的完整代码如下: 
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//ZH-CN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
   <meta http-equiv="Content-Type" content="text/html">
<head>
   <script language=JavaScript>
    function $(id)
    {
     return document.getElementById(id)
    }
    function show()
    {
     var selectObj=$("area")
     var myOption=document.createElement("option")
     myOption.setAttribute("value","10")
     myOption.appendChild(document.createTextNode("上海"))
     var myOption1=document.createElement("option")
     myOption1.setAttribute("value","100")
     myOption1.appendChild(document.createTextNode("南京"))
     selectObj.appendChild(myOption)
     selectObj.appendChild(myOption1)
    }
    function choice()
    {
     var index=$("area").selectedIndex;
     var val=$("area").options[index].getAttribute("value")