test.js

function mergeDocument() {
    TXTextControl.saveDocument(TXTextControl.streamType.InternalUnicodeFormat,
        function (e) {
            var serviceURL = "/Home/MergeDocument";

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

            function successFunc(data, status) {
                TXTextControl.loadDocument(TXTextControl.streamType.InternalUnicodeFormat, data);
            }

            function errorFunc(error) {
                console.log(error);
            }
        });
}