tx.js

function Merge() {
    // save the document
    TXTextControl.saveDocument(
        TXTextControl.streamType.InternalUnicodeFormat,
        function (e) {

            var serviceURL = "/Home/Merge";

            // call the controller
            $.ajax({
                type: "POST",
                url: serviceURL,
                contentType: 'application/json',
                data: JSON.stringify({
                    BinaryDocument: e.data
                }),
                success: successFunc,
                error: errorFunc
            });

            // the controller sends back the merged document
            // that is loaded into the editor
            function successFunc(data, status) {
                TXTextControl.loadDocument(
                    TXTextControl.streamType.InternalUnicodeFormat, data);
                alert("Document has been merged successfully.");
            }

            function errorFunc() {
                alert('Error');
            }
        });
}