当 <menu> 元素在上下文菜单显示时执行 JavaScript:
<div contextmenu="mymenu"> <p>Right-click inside this box to see the context menu! <p>用鼠标右键单击黄色框区域查看上下文菜单！</p> <menuitem label="刷新" onclick="window.location.reload();"></menuitem> </menu> </div>