<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>水果选择</title>
</head>
<style type="text/css">
select{
width: 200px;
height: 100px;
}
</style>
<body>
<h1>水果选择：</h1>
<select name="" id="left" size="2">
<option>苹果</option>
<option>橘子</option>
<option>香蕉</option>
<option>西瓜</option>
<option>草莓</option>
</select>
<input type="button" value=">>" name="" id="btn">
<select name="" id="right" size="2"></select>
</body>
<script type="text/javascript">
btn=document.getElementById('btn');
left=document.getElementById('left');
right=document.getElementById('right');
opts=left.options;
btn.onclick=function(){
idx=left.selectedIndex;
right.add(opts[idx]);
}
</script>
</html>
