<!DOCTYPE html>
<html>
<body>
<p id="demo">点击按钮来获得 button 元素的首个属性的名称。</p>
<button onclick="myFunction()">试一下</button>
<script>
function myFunction()
{
var a=document.getElementsByTagName("BUTTON")[0];
var x=document.getElementById("demo");
x.innerHTML=a.attributes.item(0).nodeName;
}
</script>
</body>
</html>