Could not get Cursor Position in a wysihtml5 editor

Question

I tried the below code I am unable to get Cursor Position in a wysihtml5 editor enter image description here

<script type="text/javascript">
      var is_gecko = /gecko/i.test(navigator.userAgent);
      var is_ie = /MSIE/.test(navigator.userAgent);

      function setSelectionRange(input, start, end) {
        if (is_gecko) {
          input.setSelectionRange(start, end);
        } else {
          // assumed IE
          var range = input.createTextRange();
          range.collapse(true);
          range.moveStart("character", start);
          range.moveEnd("character", end - start);
          range.select();
        }
      };

      function getSelectionStart(input) {
        if (is_gecko)
          return input.selectionStart;
        var range = document.selection.createRange();
        var isCollapsed = range.compareEndPoints("StartToEnd", range) == 0;
        if (!isCollapsed)
          range.collapse(true);
        var b = range.getBookmark();
        return b.charCodeAt(2) - 2;
      };

      function getSelectionEnd(input) {
        if (is_gecko)
          return input.selectionEnd;
        var range = document.selection.createRange();
        var isCollapsed = range.compareEndPoints("StartToEnd", range) == 0;
        if (!isCollapsed)
          range.collapse(false);
        var b = range.getBookmark();
        return b.charCodeAt(2) - 2;
      };

      function inputKey(input, ev) {
        setTimeout(function () {
          document.getElementById("selStart").value = getSelectionStart(input);
          document.getElementById("selEnd").value = getSelectionEnd(input);
        }, 20);
      }
      function doSelect() {
        var start = document.getElementById("selStart").value;
        var end = document.getElementById("selEnd").value;
        var input = document.getElementById("editor");
        input.focus();
        setSelectionRange(input, start, end);
      }
    </script>

I am getting Cursor position Undefined as my answer

I have attached screen shot of my error it is showing undefined in textarea

<textaraea spellcheck="false" id="editor" name="editor"  data-placeholder="Transliterated Text"  class="form-control" col="5" row="50" ></textaraea>