test.js

$(document).ready(function(){

    // event for previous tab
    $(".nav-tabs button").on("hide.bs.tab", function(){

        // previous tab name
        var oldTab = $(this).attr("aria-controls");

        // save the document to local storage
        TXTextControl.saveDocument(TXTextControl.StreamType.InternalUnicodeFormat,
                                   function (e) {
            localStorage.setItem('tx-document_' + oldTab, e.data);
        });

    });

    // event for current tab
    $(".nav-tabs button").on("show.bs.tab", function(){

        // current tab name
        var newTab = $(this).attr("aria-controls");

        // get the previously stored document from local storage
        const document = localStorage.getItem('tx-document_' + newTab);

        // if document is not null, load the document
        // and move the editorin DOM to new tab location
        if (document !== null) {

            TXTextControl.loadDocument(TXTextControl.StreamType.InternalUnicodeFormat,
                                       document, function() {
                $("#tx-editor").appendTo("#" + newTab);
            });

        }
        // if document is null, clear the Text Control and move in DOM
        else {
            TXTextControl.resetContents(function() {
                $("#tx-editor").appendTo("#" + newTab);
            });
        }

    });

});