modal

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <meta http-equiv="content-type" content="text/html; charset=utf-8" />
    <title>Jota</title>
    <link href="style.css" rel="stylesheet" type="text/css" media="screen" />
    <script>
        //configuration
        var codes = new Map();
        codes.set("1234", "output");
        codes.set("1234", "output");

        var errorMsg = "Error bericht";
    </script>
</head>
<body>

    <!-- Trigger/Open The Modal -->
    <input id="JotaCode">
    <button id="myBtn">Open Modal</button>

    <!-- The Modal -->
    <div id="myModal" class="modal">

      <!-- Modal content -->
      <div class="modal-content">
        <span class="close">&times;</span>
        <p id="modal-text">Some text in the Modal..</p>
      </div>

    </div>

    <script>
        // Get the modal
        var modal = document.getElementById("myModal");

        // Get the button that opens the modal
        var btn = document.getElementById("myBtn");

        // Get the <span> element that closes the modal
        var span = document.getElementsByClassName("close")[0];

        // Get the <p> text
        var modalText = document.getElementById("modal-text");

        // When the user clicks on the button, open the modal
        btn.onclick = function() {
            modal.style.display = "block";

            //Get the value from the map with the key from the input field
            var codeResult = codes.get(document.getElementById("JotaCode").value);

            // If a value is returned, show the text. or else show an error message
            if(codeResult != null) {
                modalText.innerHTML = codeResult;
            } else {
                modalText.innerHTML = errorMsg;
            }
        }

        // When the user clicks on <span> (x), close the modal
        span.onclick = function() {
          modal.style.display = "none";
        }

        // When the user clicks anywhere outside of the modal, close it
        window.onclick = function(event) {
          if (event.target == modal) {
            modal.style.display = "none";
          }
        }
    </script>
</body>
</html>