<html><head><style>.democlass { color: red;}</style></head><body><h1 class="democlass">Hello World</h1><p>点击按钮显示h1元素的class属性节点的值。</p><button onclick="myFunction()">试一试</button><p id="demo"></p><script>function myFunction() { var elmnt = document.getElementsByTagName("H1")[0]; var attr = elmnt.getAttributeNode("class").value; document.getElementById("demo").innerHTML = attr;}</script></body></html>