Read/write xls files with Nodejs

app.js

var express = require('express');
var Excel = require('exceljs');
var app = express();

app.listen(3000, function() {
	console.log('Trying to read a xlsx file on port 3000...');
	
	var workbook = new Excel.Workbook();
	var filename = 'InputFile.xlsx';
	const COL = 'B';
	const ROW = 20;
	// reading excel file
	workbook.xlsx.readFile(__dirname + filename).then(function() {
		// get the 2nd column ('input')
		var worksheet = workbook.getWorksheet(1);
		
		// get the B column
		var col = worksheet.getColumn(COL);
		
		// modify the B20 with 'No'
		col.eachCell(function(cell, rowNumber) {
			if (rowNumber == ROW) {
				cell.value = 'No';
			}
		});
		
		// save the content in a new file (formulas re-calculated)
		workbook.xlsx.writeFile(__dirname + '/OutputFile.xlsx');
	});
});

Your solution is for .XLSX only, not for .XLS. These formats are different completely, just extensions are like

Your solution is for .XLSX only, not for .XLS. These formats are different completely, just extensions are like

Oh, I didn't tried with xls, just xlsx, I tought it would work. My bad

Thank u