javascript 之 select下拉框

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.options.add(new   Option("文本","值"));   
  }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);
  }9.选中其中的select
opt_uprice.options[i].selected=true;