Example vlookup with node.js

vlookup.js

const fs = require('fs')
const _ = require('underscore');
const baby = require('babyparse');
const jmespath = require('jmespath');

// csv parse options
const parseOptions = {
  header: true,
  skipEmptyLines: true
};

// read files
const file1 = fs.readFileSync('file1.csv', 'utf8');
const file2 = fs.readFileSync('file2.csv', 'utf8');

// parse csv files
const parsedFile1 = baby.parse(file1, parseOptions);
const parsedFile2 = baby.parse(file2, parseOptions);

// actual logic
// add person id to order using email as lookup
_.each(parsedFile2.data, obj => {

  var idByEmail = `data[?email=='${obj.email}'].id | [0]`;
  obj.personId = jmespath.search(parsedFile1, idByEmail);

});

// write to file
const csvString = baby.unparse(parsedFile2.data);
fs.writeFile('output.csv', csvString);