index.html
<!DOCTYPE html>
<html lang="ja">
<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>My JavaScript</title>
</head>
<body>
<script src="main.js"></script>
</body>
</html>main.js
'use strict';
const fname = 'Taro';
const lname = 'Yamada';
//console.log('My name is ' + fname + ' ' + lname + ', call me ' + fname + '!');
console.log('My name is ${fname} ${lname}, call me $(fname)!');