js 操作select和option常见用法

<select id="mySelect">
<option value="1">one</option>
<option value="2">two</option>
<option value="3">three</option>
</select>

$("#mySelect").val(); //获取选中记录的value值
$("#mySelect option:selected").text(); //获取选中记录的text值 

var obj = document.getElementById("mySelect");
obj.add(new Option("4","4")); 

var obj = document.getElementById("mySelect");
obj.options.length = 0; 

var obj = document.getElementById("mySelect");
var index = obj.selectedIndex;
obj.options.remove(index);

var obj = document.getElementById("mySelect");
var index = obj.selectedIndex;
obj.options[index] = new Option("three",3); //更改对应的值
obj.options[index].selected = true; //保持选中状态

var obj = document.getElementById("mySelect");
obj.parentNode.removeChild(obj); //移除当前对象 

$("#mySelect").change(function(){ //添加所需要执行的操作代码}) 

function createSelect(){
var mySelect = document.createElement_x("select");
mySelect.id = "mySelect";
document.body.appendChild(mySelect);
} 

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")); //这个只能在IE中有效
obj.options.add(new Option("text","value")); //这个兼容IE与firefox
}

function removeAll(){
var obj=document.getElementByIdx_x(‘mySelect‘);
obj.options.length=0;
}

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);
} 

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; 

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;

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");

function removeSelect(){
var mySelect = document.getElementByIdx_x("mySelect");
mySelect.parentNode.removeChild(mySelect);
}