Untitled

<body>
    <form id="host">
        <!-- Click this button to add emails to form -->
        <button id="btn">Add email</button>
    </form>
    <script>
        // add emails to form
        function add() {
            var email = document.createElement("input");
            email.type = "email";
            email.name = "email";
            document.getElementById("host").appendChild(email);
        }
        document.getElementById("btn").addEventListener("click", add);
    </script>
</body>