How to create an Excel File with Nodejs?

excel4node is a maintained, native Excel file creator built from the official specification. It's similar to, but more maintained than mxexcel-builder mentioned in the other answer.

// Require library
var excel = require('excel4node');

// Create a new instance of a Workbook class
var workbook = new excel.Workbook();

// Add Worksheets to the workbook
var worksheet = workbook.addWorksheet('Sheet 1');
var worksheet2 = workbook.addWorksheet('Sheet 2');

// Create a reusable style
var style = workbook.createStyle({
  font: {
    color: '#FF0800',
    size: 12
  },
  numberFormat: '$#,##0.00; ($#,##0.00); -'
});

// Set value of cell A1 to 100 as a number type styled with paramaters of style
worksheet.cell(1,1).number(100).style(style);

// Set value of cell B1 to 300 as a number type styled with paramaters of style
worksheet.cell(1,2).number(200).style(style);

// Set value of cell C1 to a formula styled with paramaters of style
worksheet.cell(1,3).formula('A1 + B1').style(style);

// Set value of cell A2 to 'string' styled with paramaters of style
worksheet.cell(2,1).string('string').style(style);

// Set value of cell A3 to true as a boolean type styled with paramaters of style but with an adjustment to the font size.
worksheet.cell(3,1).bool(true).style(style).style({font: {size: 14}});

workbook.write('Excel.xlsx');

I just figured a simple way out . This works -

Just create a file with Tabs as delimiters ( similar to CSV but replace comma with Tab ). Save it with extension .XLS . The file can be opened in Excel .

Some code to help --

var fs = require('fs');
var writeStream = fs.createWriteStream("file.xls");

var header="Sl No"+"\t"+" Age"+"\t"+"Name"+"\n";
var row1 = "0"+"\t"+" 21"+"\t"+"Rob"+"\n";
var row2 = "1"+"\t"+" 22"+"\t"+"bob"+"\n";

writeStream.write(header);
writeStream.write(row1);
writeStream.write(row2);

writeStream.close();

This creates the file in XLS file format . It doesnt work if you try XLSX instead of XLS .

Use msexcel-builder. Install it with:

npm install msexcel-builder

Then:

// Create a new workbook file in current working-path 
var workbook = excelbuilder.createWorkbook('./', 'sample.xlsx')

// Create a new worksheet with 10 columns and 12 rows 
var sheet1 = workbook.createSheet('sheet1', 10, 12);

// Fill some data 
sheet1.set(1, 1, 'I am title');
for (var i = 2; i < 5; i++)
  sheet1.set(i, 1, 'test'+i);

// Save it 
workbook.save(function(ok){
  if (!ok) 
    workbook.cancel();
  else
    console.log('congratulations, your workbook created');
});

Although this question has several answers, they may now be a little dated.

New readers may prefer to consider the xlsx or "sheetsJS" package, which now seems to now be by far the most popular node package for this use case.

The current top answer recommends excel4node , which does look quite good - but the latter package seems less maintained (and far less popular) than the former.

Answering the question directly, using xlsx:

const XLSX = require('xlsx');

/* create a new blank workbook */
const wb = XLSX.utils.book_new();

// Do stuff, write data
//
//

// write the workbook object to a file
XLSX.writeFile(workbook, 'out.xlsx');

You should check ExcelJS

Works with CSV and XLSX formats.

Great for reading/writing XLSX streams. I've used it to stream an XLSX download to an Express response object, basically like this:

app.get('/some/route', function(req, res) {
  res.writeHead(200, {
    'Content-Disposition': 'attachment; filename="file.xlsx"',
    'Transfer-Encoding': 'chunked',
    'Content-Type': 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'
  })
  var workbook = new Excel.stream.xlsx.WorkbookWriter({ stream: res })
  var worksheet = workbook.addWorksheet('some-worksheet')
  worksheet.addRow(['foo', 'bar']).commit()
  worksheet.commit()
  workbook.commit()
}

Works great for large files, performs much better than excel4node (got huge memory usage & Node process "out of memory" crash after nearly 5 minutes for a file containing 4 million cells in 20 sheets) since its streaming capabilities are much more limited (does not allows to "commit()" data to retrieve chunks as soon as they can be generated)

See also this SO answer.