index.html

<!DOCTYPE html>
<html lang="pt-br">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="style.css">
    <link rel="stylesheet" href="https://pro.fontawesome.com/releases/v5.10.0/css/all.css" integrity="sha384-AYmEC3Yw5cVb3ZcuHtOA93w35dYTsvhLPVnYs9eStHfGJvOvKxVfELGroGkvsg+p" crossorigin="anonymous"/>
    <title>JS Phone Mask</title>
</head>
<body>
    <div id="app">
        <i class="fab fa-js js"></i>
        <h1>JS Brazillian Phone Mask</h1>
        <input type="text" onkeyup="phoneMask(event)" minlength="16" maxlength="16" placeholder="(99) 9 9999-9999" autofocus required>
        <p>
            <span>
                Fork by:
                <a href="https://github.com/gcairesdev" target="_blank">
                    Guilherme A. Caires
                </a>
            </span>
            <span>
                Inicial repository:
                <a href="https://github.com/mrbrunelli/regexp-celular-javascript" target="_blank">
                    Matheus R. Brunelli
                </a>
            </span>
        </p>
        <i class="fab fa-github github"></i>
    </div>
    <script src="phoneMask.js"></script>
</body>
</html>