转载于： http://blog.sina.com.cn/s/blog_4e46752f0100qujv.html

1.动态创建select
    function createSelect(){
        var mySelect = document.createElement_x("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.getElementByIdx_x('mySelect');
         //添加一个选项
         obj.add(new    Option("文本","值"));   
   }
3.删除所有选项option
   function removeAll(){
         var obj=document.getElementByIdx_x('mySelect');
  
         obj.options.length=0;  
   }
4.删除一个选项option
function removeOne(){
         var obj=document.getElementByIdx_x('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.getElementByIdx_x('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.getElementByIdx_x('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.getElementByIdx_x('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.getElementByIdx_x("mySelect");
         mySelect.parentNode.removeChild(mySelect);
   }

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