test.cshtml

@using TXTextControl.Web.MVC

@Html.TXTextControl().TextControl().Render()

<input type="button" onclick="loadDocument()" value="Load Document" />

<script>

    var connectionID;

    TXTextControl.addEventListener("textControlLoaded", function () {
        connectionID = TXTextControl.connectionID;
    });

    function loadDocument() {
      $.ajax({
              url: '@Url.Action("LoadDocument")',
              type: 'POST',
              data: { connectionID: connectionID },
      });
    }
    
</script>