<!DOCTYPE html>
<html>
<body>
<h1>input popovertargetaction 属性</h1>
<h1 popover id="myheader">Hello</h1>
<input type="button" popovertarget="myheader" popovertargetaction="show" value="显示弹出框">
<p>单击该按钮，可显示弹出框元素。</p>
</body>
</html>