<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title>列表框，下拉菜单的增删改操作</title>
<script type="text/javascript">
function createSelect(){
//创建
var select = document.createElement("select");
select.id = "city";
var body = document.getElementById("test");
body.appendChild(select);
//创建五个option
for(var i=1;i<5;i++){
var opt = new Option("值"+i,"value"+i);
select.options[i] = opt;
}
}
function delone(){
}
function clearAll(){
//只要把options的长度改为0就可以的
var city = document.getElementById("city");
city.options.length = 0;
}
</script>
</head>
<body id="test">
<input type="button" value="创建一个城市列表框" onclick="createSelect()"/>
<input type="button" value="一条条删除列表框内容" onclick="delone()"/>
<input type="button" value="一次性清空列表框内容" onclick="clearAll()"/>
</body>
</html>