js select option操作(默认选中与option选项)

发布时间:2020-07-01编辑:脚本学堂
js select option选项操作的例子,动态创建select,添加与删除选项option,获得选项option的值与文本等。

jquery select根据value默认选中

jQuery
 

$("#SelectID option[value='selectValue']").attr("selected",true)
 

注意:Option中的O是要大写的,不然语法报错  

1,动态创建select 
 

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

  
Option参数:
new   Option   (text,value,defaultselected,selected)
new   Option   (文本,值,默认选中的选项,选中的选项)  

结果:
 

<select id="s1"></select>
<script>
var  op  = new  Option("显示文本1","值1",false,false);
s1.options.add(op);
op   = new   Option("显示文本2","值2",false,true);
s1.options.add(op);
</script>  

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);
}

js select操作实例: 
 

复制代码 代码示例:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//ZH-CN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html">
<head>
<script language=javascript>
function $(id)
{
return document.getElementById(id)
}
function show()
{
var selectObj=$("area")
var myOption=document.createElement("option")
myOption.setAttribute("value","10")
myOption.appendChild(document.createTextNode("上海"))
var myOption1=document.createElement("option")
myOption1.setAttribute("value","100")
myOption1.appendChild(document.createTextNode("南京"))
selectObj.appendChild(myOption)
selectObj.appendChild(myOption1)
}
function choice()
{
var index=$("area").selectedIndex;
var val=$("area").options[index].getAttribute("value")
if(val==10)
{
var i=$("context").childNodes.length-1;
var remobj=$("context").childNodes[i];
remobj.removeNode(true)
var sh=document.createElement("select")
sh.add(new Option("浦东新区","101"))
sh.add(new Option("黄浦区","102"))
sh.add(new Option("徐汇区","103"))
sh.add(new Option("普陀区","104"))
$("context").appendChild(sh)
}
if(val==100)
{
var i=$("context").childNodes.length-1;
var remobj=$("context").childNodes[i];
remobj.removeNode(true)
var nj=document.createElement("select")
nj.add(new Option("玄武区","201"))
nj.add(new Option("白下区","202"))
nj.add(new Option("下关区","203"))
nj.add(new Option("栖霞区","204"))
$("context").appendChild(nj)
}
}
function calc()
{
var x=$("context").childNodes.length-1;
alert(x)
}
function remove()
{
var i=$("context").childNodes.length-1;
var remobj=$("context").childNodes[i];
remobj.removeNode(true)
}
</script>
<body>
<div id="context">
<select id="area" onchange="choice()">
</select>
</div>
<input type=button value="显示" onclick="show()">
<input type=button value="计算结点" onclick="calc()">
<input type=button value="删除" onclick="remove()">
</body>
</html>

改进版:select option元素的添加、修改与删除操作 
 

复制代码 代码示例:
function watch_ini(){ // 初始
for(var i=0; i<arguments.length; i++){
var word = document.createElement("OPTION");
word.text = arguments[i];
watch.keywords.add(word); // watch. is form name
}
}
function watch_add(f){ // 增加
var word = document.createElement("OPTION");
word.text = f.word.value;
f.keywords.add(word);
}

以上的add()方法只在IE下有效,为兼容FF和Opera,改动后代码:
 

复制代码 代码示例:
function watch_ini(){ // 初始  
for(var i=0; i<arguments.length; i++){
var oOption=new Option(arguments[i],arguments[i]);
document.getElementById("MySelect")[i]=oOption;
}
}
function watch_add(f){ // 增加
var oOption=new Option(f.word.value,f.word.value);
f.keywords[f.keywords.length]=oOption;
}

改进的js select操作的完整代码: 
 

复制代码 代码示例:
<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
<html>
<head>
<title>javascript select options text value</title>
<meta name="keywords" content="javascript select options text value add modify delete set">
<meta name="description" content="javascript select options text value add modify delete set">
<script language="javascript">
<!--
function watch_ini(){ // 初始
for(var i=0; i<arguments.length; i++){
var oOption=new Option(arguments[i],arguments[i]);
document.getElementById("MySelect")[i]=oOption;
}
}
function watch_add(f){ // 增加
var oOption=new Option(f.word.value,f.word.value);
f.keywords[f.keywords.length]=oOption;
}
function watch_sel(f){ // 编辑
f.word.value = f.keywords[f.keywords.selectedIndex].text;
}
function watch_mod(f){ // 修改
f.keywords[f.keywords.selectedIndex].text = f.word.value;
}
function watch_del(f){ // 删除
f.keywords.remove(f.keywords.selectedIndex);
}
function watch_set(f){ // 保存
var set = "";
for(var i=0; i<f.keywords.length; i++){
set += f.keywords[i].text + ";";
}
confirm(set);
}
//-->
</script>
</head>
<body>
<form name="watch" method="post" action="">
<select id="MySelect" name="keywords" size="10" onchange="watch_sel(this.form)"></select><br>
<script language="javascript">
<!--
watch_ini("我","你","妳","他","她","它","尔"); // 初始关键词
//-->
</script>
<input type="text" name="word" /><br />
<input type="button" value="增加" onclick="watch_add(this.form);" />
<input type="button" value="修改" onclick="watch_mod(this.form);" />
<input type="button" value="删除" onclick="watch_del(this.form);" />
<input type="button" value="保存" onclick="watch_set(this.form);" />
</form>
</body>
</html>