JS动态操作select的option

   //动态创建select
 function createSelect()
 ...{
 var mySelect = document.createElement("select");
 mySelect.id = "mySelect";
 document.body.appendChild(mySelect);
 } 
			

				 
		

			

				 
			

				 //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
			

				} 
			

				 
		

  //删除所有选项option
 
			

				function removeAll()
			

				...{
			

				var obj=document.getElementById('mySelect');
			

				obj.options.length=0;
			

				}
			

				 
		

			

				 
			

				    //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);
			

				} 
			

				 
		

			

				 
			

				    //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; 
			

				 
		

			

				 
			

				    //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");