Script to parse list of barcodes and append additional UPC/ISBN info

parse.js

var fs = require('fs');
var fileName = process.argv[2];

var barcodes = readFile(fileName, 'utf8')
	.then(data => data.split(/\r\n/g))
	.then(lines => lines
		.slice(1)
		.map(line => line.split(/,/g))
		.map(a => {
			return {
				barcode: a[0],
				type: a[1],
				scanDate: a[2],
			};
		}));
var additionalInfo = barcodes
	.then(b => b.map(o => readFile(`json/${o.barcode}.json`, 'utf8')))
	.then(promises => Promise.all(promises))
	.then(jsons => jsons
		.map(JSON.parse)
		.reduce((a, b) => a.concat(b), [])
		.reduce((prev, curr) => {
			prev[curr.Barcode] = curr;
			return prev;
		}, {}));

Promise.all([barcodes, additionalInfo])
	.then(values => {
		var bs = values[0];
		var is = values[1];

		return bs
			.map(b => {
				var info = is[b.barcode];
				if (info) {
					b.name = info.Name;
					b.manufacturer = info.Manufacturer;				
				}
				return b;
			})
			.map(b => ['scanDate', 'barcode', 'type', 'name', 'manufacturer']
					.map(key => b[key] || '')
					.map(value => `"${value.replace(/"/g, '\\"')}"`)
					.join(','))
		;
	})
	.then(lines => lines.map(log));

function readFile(filename, enc){
  return new Promise(function (fulfill, reject){
    fs.readFile(filename, enc, function (err, res){
      if (err) reject(err);
      else fulfill(res);
    });
  });
}

function log(value) {
	console.log(value)
	return value;
}