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.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);
   }