<html><body><h1>Window 对象</h1><h2>matchMedia() 方法</h2><p id="demo"></p><script>let text;if (matchMedia("(max-width: 700px)").matches) { text = "屏幕宽度小于或等于 700 像素。";} else { text = "屏幕至少有 700 像素宽。";}document.getElementById("demo").innerHTML = text;</script></body></html>