javaScript简介
javaScript语句、标识符
变量
var num =10;
var就是固定声明,num就是变量名，10就是变量；
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title></title>
</head>
<body>
<script>
var num = 10;
console.log(num)
</script>
</body>
</html>
JavaScript引入到文件
嵌入到html文件中
<body>
<script>
var num = 10;
console.log(num)
</script>
</body>
引入本地独立js文件中
<body>
<script src="./hellojs.js"></script>
</body>
var age = 20;
console.log(age)
引入网络来源文件
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title></title>
/*引入外部文件*/
<script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
</head>
<body>
</body>
</html>
