<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>水果选择</title> </head> <style type="text/css"> select{ 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>