JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://rawgit.com/eligrey/FileSaver.js/master/FileSaver.js"></script>
<script src="http://requirejs.org/docs/release/2.1.14/minified/require.js"></script>
<script src="https://rawgit.com/stephenliberty/excel-builder.js/master/dist/excel-builder.compiled.min.js"></script>
<button id=btn>Clique!</button>

JavaScript

require(['excel-builder'], function(E) { window.Excel = E; });

btn.onclick = function() {
    var workbook = Excel.createWorkbook();
    var sheet = workbook.createWorksheet({name: "Teste de Moeda"});
    workbook.addWorksheet(sheet);
    
    var currency = workbook.getStyleSheet().createFormat({
        format: "#,##0.00"
    });
    
    var data = [[ // Essa é a célula A1
        {value: 1234567.89, // Deve exibir como "1.234.567,89" no excel
         metadata: {style: currency.id}}
    ]];
    
    sheet.setData(data);
    sheet.setColumns([{width: 15}]);
    saveAs(Excel.createFile(workbook, {type: "blob"}), "moeda.xlsx");
}