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');
	});
});