代码示例:(标识:jsck_win_matchmedia_2)
<!DOCTYPE html>
<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>
运行结果: