for_peter.js

const request = require('request'); // To hit the API
const fs = require('fs');
const csv = require('csv-write-stream'); // To output a .csv
const jsonfile = require('jsonfile'); // To parse a .json file
const async = require('async'); // To make sure the program excutes top down

newArray = [];

// Begin async execution
async.waterfall([
    consumeJsonFile,
    consumeApi,
    buildNewObject,
    outputCSV
], function(err, result) {
    if (err) {
        throw err;
    } else {
        // console.log(result);
    }
});

function consumeJsonFile(callback) {

    var file = 'dnis.json';

    jsonfile.readFile(file, function(err, obj) {
        let jsonData = obj;
        callback(null, jsonData);
    });

}

function consumeApi(jsonData, callback) {

    var file = 'db.json';

    jsonfile.readFile(file, function(err, obj) {
        let apiData = obj;
        callback(null, jsonData, apiData);
    });

}

function buildNewObject(jsonData, apiData, callback) {

    jsonData.forEach(function(element, i) {

        let result = apiData.filter(function(obj) {
            return obj.DnisId == element.dnis;
        });

        newArray.push(result[0]);

    });

    callback(null, newArray);
}

function outputCSV(newArray, callback) {

    let writer = csv();

    writer.pipe(fs.createWriteStream('truantOffices.csv'));

    newArray.forEach(function(element, i) {

      if (element !== undefined) {
        writer.write({
            DnisId: element.DnisId,
            InternalName: element.InternalName,
            Name: element.Name,
            PhoneNumber: element.PhoneNumber,
            Five9DnisID: element.Five9DnisID,
            OfficeId: element.OfficeId
        });
      }

    });

    writer.end();

    callback(null, newArray);
}