Javascript json to xlsx trello

I'm not an expert in javascript but I'm trying to modify an extension that takes the json that Trello exports and converts it to an excel format, the extension works great ... but I would like to also extract the date of each card , which according to the json is "dateLastActivity:" but it is difficult to understand the extension js, here is the js github so you can see it export for trello

//globals
    var $,
    byteString,
    xlsx,
    ArrayBuffer,
    Uint8Array,
    Blob,
    saveAs;


// Variables
var $excel_btn,
    addInterval,
    columnHeadings = ['List', 'Title', 'Description', 'Points', 'Due', 'Members', 'Labels', 'Card #', 'Card URL']; //aqui va las cabeceras del excel

window.URL = window.webkitURL || window.URL;

function createExcelExport() {
    "use strict";
    // RegEx to find the points for users of TrelloScrum
    var pointReg = /[\(](\x3f|\d*\.?\d+)([\)])\s?/m;

    var boardExportURL = $('a.js-export-json').attr('href');
    //RegEx to extract Board ID
    var parts = /\/b\/(\w{8})\.json/.exec(boardExportURL);

    if(!parts) {
        alert("Board menu not open.");
        return;
    }

    var idBoard = parts[1];
    var apiURL = "https://trello.com/1/boards/" + idBoard + "?lists=all&cards=all&card_attachments=cover&card_stickers=true&card_fields=badges%2Cclosed%2CdateLastActivity%2Cdesc%2CdescData%2Cdue%2CidAttachmentCover%2CidList%2CidBoard%2CidMembers%2CidShort%2Clabels%2CidLabels%2Cname%2Cpos%2CshortUrl%2CshortLink%2Csubscribed%2Curl&card_checklists=none&members=all&member_fields=fullName%2Cinitials%2CmemberType%2Cusername%2CavatarHash%2Cbio%2CbioData%2Cconfirmed%2Cproducts%2Curl%2Cstatus&membersInvited=all&membersInvited_fields=fullName%2Cinitials%2CmemberType%2Cusername%2CavatarHash%2Cbio%2CbioData%2Cconfirmed%2Cproducts%2Curl&checklists=none&organization=true&organization_fields=name%2CdisplayName%2Cdesc%2CdescData%2Curl%2Cwebsite%2Cprefs%2Cmemberships%2ClogoHash%2Cproducts&myPrefs=true&fields=name%2Cclosed%2CdateLastActivity%2CdateLastView%2CidOrganization%2Cprefs%2CshortLink%2CshortUrl%2Curl%2Cdesc%2CdescData%2Cinvitations%2Cinvited%2ClabelNames%2Cmemberships%2Cpinned%2CpowerUps%2Csubscribed";

    $.getJSON(apiURL, function (data) {

        var file = {
            worksheets: [[], []], // worksheets has one empty worksheet (array)
            creator: 'TrelloExport',
            created: new Date(),
            lastModifiedBy: 'TrelloExport',
            modified: new Date(),
            activeWorksheet: 0
        },

            // Setup the active list and cart worksheet
            w = file.worksheets[0],
            wArchived = file.worksheets[1],
            buffer,
            i,
            ia,
            blob,
            board_title;

        w.name = data.name.substring(0, 22);  // Over 22 chars causes Excel error, don't know why
        w.data = [];
        w.data.push([]);
        w.data[0] = columnHeadings;


        // Setup the archive list and cart worksheet
        wArchived.name = 'Archived ' + data.name.substring(0, 22);
        wArchived.data = [];
        wArchived.data.push([]);
        wArchived.data[0] = columnHeadings;

        // This iterates through each list and builds the dataset
        $.each(data.lists, function (key, list) {
            var list_id = list.id,
                listName = list.name;

            // tag archived lists
            if (list.closed) {
                listName = '[archived] ' + listName;
            }

            // Iterate through each card and transform data as needed
            $.each(data.cards, function (i, card) {
                if (card.idList === list_id) {
                    var title = card.name,
                        parsed = title.match(pointReg),
                        points = parsed ? parsed[1] : '',
                        due = card.due || '',
                        memberIDs,
                        memberInitials = [],
                        labels = [],
                        d = new Date(due),
                        rowData = [],
                        rArch,
                        r;

                    title = title.replace(pointReg, '');

                    // tag archived cards
                    if (card.closed) {
                        title = '[archived] ' + title;
                    }

                    memberIDs = card.idMembers;
                    $.each(memberIDs, function (i, memberID) {
                        $.each(data.members, function (key, member) {
                            if (member.id === memberID) {
                                memberInitials.push(member.initials);
                            }
                        });
                    });

                    //Get all labels
                    $.each(card.labels, function (i, label) {
                        if (label.name) {
                            labels.push(label.name);
                        } else {
                            labels.push(label.color);
                        }

                    });

                    // Need to set dates to the Date type so xlsx.js sets the right datatype
                    if (due !== '') {
                        due = d;
                    }

                    rowData = [
                        listName,
                        title,
                        card.desc,
                        points,
                        due,
                        memberInitials.toString(),
                        labels.toString(),
                        card.idShort,
                        card.shortUrl
                    ];

                    // Writes all closed items to the Archived tab
                    // Note: Trello allows open cards on closed lists
                    if (list.closed || card.closed) {
                        rArch = wArchived.data.push([]) - 1;
                        wArchived.data[rArch] = rowData;

                    } else {
                        r = w.data.push([]) - 1;
                        w.data[r] = rowData;
                    }
                }
            });
        });

        // We want just the base64 part of the output of xlsx.js
        // since we are not leveraging they standard transfer process.
        byteString = window.atob(xlsx(file).base64);
        buffer = new ArrayBuffer(byteString.length);
        ia = new Uint8Array(buffer);

        // write the bytes of the string to an ArrayBuffer
        for (i = 0; i < byteString.length; i += 1) {
            ia[i] = byteString.charCodeAt(i);
        }

        // create blob and save it using FileSaver.js
        blob = new Blob([ia], {
            type: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'
        });
        board_title = data.name;
        saveAs(blob, board_title + '.xlsx');
        $("a.pop-over-header-close-btn")[0].click();


    });

}


// Add a Export Excel button to the DOM and trigger export if clicked
function addExportLink() {
    "use strict";
    //alert('add');

    var $js_btn = $('a.js-export-json'); // Export JSON link

    // See if our Export Excel is already there
    if ($('.pop-over-list').find('.js-export-excel').length) {
        clearInterval(addInterval);
        return;
    }

    // The new link/button
    if ($js_btn.length) {
        $excel_btn = $('<a>')
            .attr({
                'class': 'js-export-excel',
                'href': '#',
                'target': '_blank',
                'title': 'Open downloaded file with Excel'
            })
            .text('Exportar a Excel')
            .click(createExcelExport)
            .insertAfter($js_btn.parent())
            .wrap(document.createElement("li"));

    }
}


// on DOM load
$(function () {
    "use strict";
    // Look for clicks on the .js-share class, which is
    // the "Share, Print, Export..." link on the board header option list
    $(document).on('mouseup', ".js-share", function () {
        addInterval = setInterval(addExportLink, 500);
    });
});

pdt: basically the extension works in this way, when you enter the configuration of the trello and the option to export only gives you the option to export as json, the extension modifies the sun and adds an option that says export in excel and generates the excel.

pdt2: to modify an extension google will not recognize it, I recommend activating the developer mode in extensions manager, and in the option, 'load extension without packaging' and add the folder that you download from the github

I will also modify it if I can share it right here ... thanks in advance and let me know if I break any rule to eliminate the question ... thanks