<!DOCTYPE html> <html> <body> <h1>Element 对象</h1> <h2>insertAdjacentHTML() 方法</h2> <button onclick="myFunction()">插入</button> <p>单击“插入”可在标题前插入一个 span:</p> <h2 id="myH2">我的标题</h2> <script> function myFunction() { const h2 = document.getElementById("myH2"); let html = "<span style='color:red'>我的 span</span>"; h2.insertAdjacentHTML("beforebegin", html); } </script> </body> </html>