首先我们创建一个 html 文件
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport"
content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
</head>
<body>
<script>
var a = 10;
var b = 10;
function add (a, b){
return a + b
}
var c = add(a, b)
</script>
</body>
</html>
