In-browser js spreadsheets generation library

example.html

 <script>
        $('#export').on('click', function () {
            var tableContent = taffyData[0].content;
          
            var excelSheetElements = {
                name: 'My fees', // Name of the sheet (tabs)
                data: tableContent.map(function (el) { // An array of array containing data (each element is a line)
                    return [el.date, el.label, el.amount]
                })
            };

            foncia.export_excel.exportDocument('My site - My fees ' + new Date().toLocaleDateString(), excelSheetElements)
        });
</script>

in-browser-spreadsheet-export.js

var screamz = screamz || {};
screamz.spreadsheets_export = (function ($, ns) {

    /**
     * An element that will be exposed for Excel download
     * @typedef {Object} ExcelSheetElement
     *
     * @property {string} name - Indicates the sheet name in the workbook.
     * @property {array} data - The line that needs to be printed
     */

    /**
     * Trigger the download of an Excel's like document based on the data you provided.
     *
     * @param {string} documentName - The downloaded document name.
     * @param {ExcelSheetElement|ExcelSheetElement[]} excelSheetElements - The data or an array of data.
     */
    ns.generateSpreadSheet = function generateSpreadSheet (documentName, excelSheetElements) {
        if (!Array.isArray(excelSheetElements)) {
            excelSheetElements = [excelSheetElements];
        }
        var workBook = new Workbook();

        excelSheetElements.forEach(function (el) {
            var workSheet = sheet_from_array_of_arrays(el.data);

            workBook.SheetNames.push(el.name);
            workBook.Sheets[el.name] = workSheet;
        });

        var wbout = XLSX.write(workBook, {bookType: 'xlsx', bookSST: true, type: 'binary'});

        saveAs(new Blob([s2ab(wbout)], {type: "application/octet-stream"}), documentName + ".xlsx")
    };

    function datenum(v) {
        var epoch = Date.parse(v);
        return (epoch - new Date(Date.UTC(1899, 11, 30))) / (24 * 60 * 60 * 1000);
    }

    function sheet_from_array_of_arrays(data) {
        var ws = {};
        var range = {s: {c: 10000000, r: 10000000}, e: {c: 0, r: 0}};
        for (var R = 0; R != data.length; ++R) {
            for (var C = 0; C != data[R].length; ++C) {
                if (range.s.r > R) range.s.r = R;
                if (range.s.c > C) range.s.c = C;
                if (range.e.r < R) range.e.r = R;
                if (range.e.c < C) range.e.c = C;
                var cell = {v: data[R][C]};
                if (cell.v == null) continue;
                var cell_ref = XLSX.utils.encode_cell({c: C, r: R});

                if (typeof cell.v === 'number') cell.t = 'n';
                else if (typeof cell.v === 'boolean') cell.t = 'b';
                else if (cell.v instanceof Date) {
                    cell.t = 'n';
                    cell.z = XLSX.SSF._table[14];
                    cell.v = datenum(cell.v);
                }
                else cell.t = 's';

                ws[cell_ref] = cell;
            }
        }
        if (range.s.c < 10000000) ws['!ref'] = XLSX.utils.encode_range(range);
        return ws;
    }

    function Workbook() {
        if (!(this instanceof Workbook)) return new Workbook();
        this.SheetNames = [];
        this.Sheets = {};
    }

    function s2ab(s) {
        var buf = new ArrayBuffer(s.length);
        var view = new Uint8Array(buf);
        for (var i = 0; i != s.length; ++i) view[i] = s.charCodeAt(i) & 0xFF;
        return buf;
    }

    return ns;
})(jQuery, {});