<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
<script type="text/javascript">
var str="hell21o worl345d!";
var reg=/\d{4,}/;
//alert(reg.test(str));
//alert(str.match(reg));
//alert(str.search(reg));
function getCity(){
var objCity=document.getElementById("city");
var objInfo=document.getElementById("info");
//选项的数量
var length=objCity.length;
objInfo.innerHTML="选项的数量： "+length+"<br/>";
//获取所有选项
objInfo.innerHTML+="获取所有选项：";
for(var i=0;i<objCity.length;i++){
objInfo.innerHTML+=objCity.options[i].text;
}
//获取当前选中的选项
var index=objCity.selectedIndex;
objInfo.innerHTML+="<br/>当前选中的项："+objCity.options[index].text;
objInfo.innerHTML+="<br/>当前选中项："+objCity.value;
objInfo.innerHTML+="<br/>当前选中项："+objCity.options[index].value;
}
//添加城市
function addCity(){
var objCity=document.getElementById("city");
var option=document.createElement("option");
option.text="无锡";
option.value="wuxi";
objCity.add(option,null);
}
//改变颜色
function changeColor(){
var objColor=document.getElementById("color");
document.bgColor=objColor.value;
}
</script>
</head>
<body>
<input type="button" value="添加" onclick="addCity()" />
<br/>
<select id="city" onchange="getCity();">
<option value="0">--城市--</option>
<option value="nanjing">南京</option>
<option value="shanghai">上海</option>
<option value="beijing">北京</option>
<option value="shenzhen">深圳</option>
</select>
<div id="info"></div>
<select id="color" onchange="changeColor();">
<option value="red">红</option>
<option value="yellow">黄</option>
<option value="blue">蓝</option>
<option value="green">绿</option>
<option value="pink">粉</option>
<option value="gray">灰</option>
<option value="black">黑</option>
<option value="orange">橙</option>
<option value="purple">紫</option>
</select>
</body>
</html>原文地址：http://blog.csdn.net/wangzi11322/article/details/45289333
