JS的引入
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<script>
// 弹窗
// alert(123)
</script>
<script src="common.js"></script>
</head>
<body>
<h1>welcome to JS!</h1>
</body>
</html>
alert(123)
console.log("hello JS")