node.js connecting to s3 and youtube

Question

I have a task to connect to S3 get a JSON file with the names of artists, use the youtube-data-api and search for the top 10 songs. Then send it back in a given format to S3 back.

console.log("Loading up the best code ever!!!");
//packagess import
var fs = require('fs');
var AWS = require('aws-sdk');
var Singer = require('./Singer')
//prepare all the AWS S3 data
AWS.config.update({ region: "us-west-1" });
var credentials = new AWS.SharedIniFileCredentials();
AWS.config.credentials = credentials;
// Create S3 service object
s3 = new AWS.S3({ apiVersion: '2006-03-01' });
// Create the parameters for calling createBucket
var bucketParams = {
 Bucket: 'pc-backend-exercises',
 Key: 'toSearch.json',
 ResponseContentType: 'application/json'
};
/// prepare the youtube-data-api
var YTAPI = require('node-youtubeapi-simplifier');
var APIKEY = 'AIzaSyDS1p3m9wnZLLCPc1hDQBX3K_UnS4j0CdY' 
YTAPI.setup(APIKEY);
console.log('connecting to s3 to get the json file');
var singers = [];
s3.getObject(bucketParams, function (err, data) {
 // Handle any error and exit
 if (err) {
 console.log(err, err.stack);
 return err;
 }
 var fileContents = data.Body.toString();
 var json = JSON.parse(fileContents);
 for (var i = 0; i < json.Search.artists.length; i++) {
 var newSinger = new Singer(json.Search.artists[i]);
 singers.push(newSinger);
 }
 console.log('the list of the singers has %d singers',json.Search.artists.length);
 search10TopForASinger();
});
//this function searches using youtube-api-simplfier for each artist name
//returns the list of songs and collects only 10, stores them into a map in the singer object
function search10TopForASinger() {
 console.log('entered search10TopForASinger ')
 var promises = [];
 for (var i = 0; i < singers.length; i++) {
 //Gets only 10 results
 promises.push(YTAPI.searchFunctions.simpleSearch(singers[i].name));
 }
 Promise.all(promises)
 .then((results) => {
 console.log('all the threads of the youtube api are back')
 for (var i = 0; i < singers.length; i++) {
 setSongsArray(results[i], singers[i].songs);
 }
 printJsonAndUpload();
 console.log('we are done you can test yourself with testGiladFile.js');
 })
 .catch((e) => {
 // Handle errors here
 });
}
//sets 10 or less songs for each artist into an array 
//we use the Singer object in order to store the data
function setSongsArray(data, songs) {
 console.log('entered setSongsArray')
 var size = 10;
 if (data.length < 10) {
 size = data.length;
 }
 for (var i = 0; i < size; i++) {
 songs.push(data[i].title);
 }
}
//The team wanted a json file with a certain format
//we create here to format and upload it back to S3
function printJsonAndUpload() {
 console.log('entered printJson')
 var data = {
 results: []
 };
 for (var i = 0; i < singers.length; i++) {
 var singerName = singers[i].name;
 var singerObj = {}
 singerObj[singerName] = []
 for (var song = 0; song < singers[i].songs.length; song++) {
 var songObj = {};
 songObj[song+1] = singers[i].songs[song];
 singerObj[singerName].push(songObj)
 }
 data.results.push(singerObj);
 }
 console.log('uploading file to s3')
 s3.putObject({Bucket: 'pc-backend-exercises',Key:'gilad.json',Body: JSON.stringify(data), ContentType: "application/json"},
 function(err, data) {
 //console.log('error');
 //console.log(JSON.stringify(err)+" "+JSON.stringify(data));
 });
 console.log('the name of the file is gilad.json');
}

This is the first code I have ever written in Node.js, please give me any feedback about style and performance.

Answer 1

I had a crack at it, I tried to replace the for loops with higher-order functions, and use ES6 let and const for variable declarations. I feel like the efficiency of the functions could be improved, but this could be a good starting point to refactoring. Also, fixed some formatting to make it a bit easier to read.

const AWS = require('aws-sdk');
const fs = require('fs');
const Singer = require('./Singer')
const YTAPI = require('node-youtubeapi-simplifier');
const credentials = new AWS.SharedIniFileCredentials();
const s3 = new AWS.S3({ apiVersion: '2006-03-01' }); //does s3 need to be declared as variable?
const APIKEY = 'AIzaSyDS1p3m9wnZLLCPc1hDQBX3K_UnS4j0CdY' 
const bucketParams = {
 Bucket: 'pc-backend-exercises',
 Key: 'toSearch.json',
 ResponseContentType: 'application/json'
};
AWS.config.update({ region: "us-west-1" });
AWS.config.credentials = credentials;
YTAPI.setup(APIKEY);
const singers = []; //do you need this singers array?
s3.getObject(bucketParams, (err, data) => {
 if (err) {
 console.log(err, err.stack);
 return err;
 }
 let fileContents = data.Body.toString();
 let json = JSON.parse(fileContents);
 //I try to avoid for loops if possible
 json.Search.artists.forEach((artist, idx) => singers.push(new Singer(json.Search.artists[idx])));
 console.log('the list of the singers has %d singers',json.Search.artists.length);
 search10TopForASinger();
});
const setSongsArray = (data, songs) => {
 data.slice(0, 10).forEach((song) => songs.push(song.title));
}
const search10TopForASinger = () => {
 console.log('entered search10TopForASinger ')
 let promises = singers.map((singer, idx) => YTAPI.searchFunctions.simpleSearch(singers[idx].name));
 Promise.all(promises).then((results) => {
 console.log('all the threads of the youtube api are back')
 singers.forEach((singer, idx) => setSongsArray(results[idx], singers[idx].songs) )
 printJsonAndUpload();
 console.log('we are done you can test yourself with testGiladFile.js');
 }).catch((e) => {
 console.log(e)
 });
}
const printJsonAndUpload = () => {
 console.log('entered printJson')
 const data = {
 results: []
 };
 singers.forEach((singer, idx) => {
 let singerName = singers[idx].name;
 const singerObj = {};
 singerObj[singerName] = [];
 singers[idx].songs.forEach((song) => { //could use .reduce() here
 const songObj = {};
 songObj[song+1] = singers[i].songs[song];
 singerObj[singerName].push(songObj)
 });
 data.results.push(singerObj);
 });
 console.log('uploading file to s3')
 s3.putObject({ Bucket: 'pc-backend-exercises', Key:'gilad.json', Body: JSON.stringify(data), ContentType: "application/json" },
 (err, data) => {
 //console.log('error');
 //console.log(JSON.stringify(err)+" "+JSON.stringify(data));
 });
 console.log('the name of the file is gilad.json');
}