代码示例:(标识:eg_js_jquery_dom_getelementsbytagname)
<!DOCTYPE html>
<html>
<body>

<h1>通过标签名查找 HTML 元素</h1>

<p>Hello World!</p>
<p>Hello China!</p>
<p>Hello Shanghai!</p>

<p id="demo"></p>

<script>
var myElements = document.getElementsByTagName("p");
document.getElementById("demo").innerHTML = "第三段中的文本是:" + myElements[2].innerHTML;
</script>

</body>
</html>
运行结果: