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

<h1>JavaScript 字符串</h1>

<h2>toUpperCase() 方法</h2>

<p>toUpperCase() 将字符串转换为大写字母:</p>

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

<script>
let text = "Hello World!";
let result = text.toUpperCase();

document.getElementById("demo").innerHTML = result;
</script>

</body>
</html>
运行结果: