<!DOCTYPE html> <html> <body> <h1>Window 对象</h1> <h2>self 和 top 属性</h2> <p id="demo"></p> <script> let text; if (window.top != window.self) { text = "这不是最顶层的窗口!我在框架中吗?"; } else { text = "这是最顶层的窗口!"; } document.getElementById("demo").innerHTML = text; </script> </body> </html>