如何使用JS动态加载option下拉选择框

//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")); //方法一：
obj.options.add(new Option("text","value")); //方法二：
for(var i=0;i<10;i++){
obj.options[i]=new Option("新文本","新值"); //方法三：
}
}

//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');
var index=obj.selectedIndex; //index,要删除选项的序号
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;
var val = obj.options[index].text;

//7.修改选项option
var obj=document.getElementById('mySelect');
var index=obj.selectedIndex;
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);
}

来源：慕课网
作者：xgqfrms2015