A JavaScript program cannot run on its own, it needs to be embedded in HTML before the browser can execute the JavaScript code. pass
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>JavaScript 基础 - 引入方式</title>
</head>
<body>
<!-- 内联形式:通过 script 标签包裹 JavaScript 代码 -->
<script>
alert('嗨,欢迎来传智播学习前端技术!')
</script>
</body>
</html>
2. External form
Generally, JavaScript code is written in a separate file ending with .js, and then passed
// demo.js
document.write('嗨,欢迎来传智播学习前端技术!')
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>JavaScript 基础 - 引入方式</title>
</head>
<body>
<!-- 外部形式:通过 script 的 src 属性引入独立的 .js 文件 -->
<script src="demo.js"></script>
</body>
</html>
Note: If the script tag imports a .js file using the src attribute, the tag's code will be ignored! ! ! As shown in the following code:
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>JavaScript 基础 - 引入方式</title>
</head>
<body>
<!-- 外部形式:通过 script 的 src 属性引入独立的 .js 文件 -->
<script src="demo.js">
// 此处的代码会被忽略掉!!!!
alert(666);
</script>
</body>
</html>