Node.js for everyone

Slides from an internal Node.js course for the Nielsen Marketing Cloud R&D developers

Transcript

1. FOR EVERYONE MAY 2017, NIELSEN MARKETING CLOUD
2. AGENDA Intro to Node.js - architecture, blocking vs. non-blocking code, event loop, reading files, issuing requests Events and Streams - reading, writing, piping, event emitters, event listening Modules - exporting, importing, NPM, Yarn, dependencies, semantic versioning Express - routes, middlewares, views, express servers Working with data - JSON Part 1 Testing - sinon, mocking, proxyquire, tape, coverage Processes & Clusters - child process, why cluster, process managers Best Practices - error handling, debugging, logging, monitoring, security Part 2
3. MILESTONES 2009 - Created by Ryan Dahl, first preview of NPM 2010 - Express, socket.io, v0.2.0 2011 - Node.js in production at Uber & Linkedin, NPM 1.0 2012 - Node.js creator Ryan Dahl steps away from Node day-to-day, v0.8.0 2013 - The MEAN Stack, eBay’s First Node.js Application, Node.js Memory Leak at Walmart 2014 - Node.js Advisory Board, IO.js – Evented I/O for V8 Javascript 2015 - IO.js 1.0.0, Node.js Foundation(Joyent, IBM, Microsoft, PayPal, Fidelity, SAP and The Linux Foundation), Node.js and io.js are merging, v4.0 is the new v1.0 2016 - v6.0: 93% support in ES2015 2017 - v7.x: 97% support in ES2015 including async/await
4. "A PLATFORM BUILT ON CHROME’S JAVASCRIPT RUNTIME FOR EASILY BUILDING FAST, SCALABLE NETWORK APPLICATIONS." What is Node?
5. “USES AN EVENT-DRIVEN, NON- BLOCKING I/O MODEL THAT MAKES IT LIGHTWEIGHT AND EFFICIENT.” What is Node?
6. BLOCKING VS. NON BLOCKING IO const getUserSync = require('./get-user-sync') const user1 = getUserSync(1) console.log('user1', user1) const user2 = getUserSync(2) console.log('user2', user2) const sum = 1 + 1 console.log(`The sum is ${sum}`) 1 2 3 4 5 6 7 const getUser = require('./get-user') getUser(1, (user1) => { console.log('user1', user1) }) getUser(2, (user2) => { console.log('user2', user2) }) const sum = 1 + 1 console.log(`The sum is ${sum}`) 1 2 3 4 5 6 7 blocking non-blocking
7. BLOCKING VS. NON BLOCKING IO const getUserSync = require('./get-user-sync') const user1 = getUserSync(1) console.log('user1', user1) const user2 = getUserSync(2) console.log('user2', user2) const sum = 1 + 1 console.log(`The sum is ${sum}`) 1 2 3 4 5 6 7 waiting on user1 const getUser = require('./get-user') getUser(1, (user1) => { console.log('user1', user1) }) getUser(2, (user2) => { console.log('user2', user2) }) const sum = 1 + 1 console.log(`The sum is ${sum}`) 1 2 3 4 5 6 7 blocking non-blocking
8. BLOCKING VS. NON BLOCKING IO const getUserSync = require('./get-user-sync') const user1 = getUserSync(1) console.log('user1', user1) const user2 = getUserSync(2) console.log('user2', user2) const sum = 1 + 1 console.log(`The sum is ${sum}`) 1 2 3 4 5 6 7 waiting on user1 printing user1 const getUser = require('./get-user') getUser(1, (user1) => { console.log('user1', user1) }) getUser(2, (user2) => { console.log('user2', user2) }) const sum = 1 + 1 console.log(`The sum is ${sum}`) 1 2 3 4 5 6 7 blocking non-blocking
9. BLOCKING VS. NON BLOCKING IO const getUserSync = require('./get-user-sync') const user1 = getUserSync(1) console.log('user1', user1) const user2 = getUserSync(2) console.log('user2', user2) const sum = 1 + 1 console.log(`The sum is ${sum}`) 1 2 3 4 5 6 7 waiting on user1 printing user1 waiting on user2 const getUser = require('./get-user') getUser(1, (user1) => { console.log('user1', user1) }) getUser(2, (user2) => { console.log('user2', user2) }) const sum = 1 + 1 console.log(`The sum is ${sum}`) 1 2 3 4 5 6 7 blocking non-blocking
10. BLOCKING VS. NON BLOCKING IO const getUserSync = require('./get-user-sync') const user1 = getUserSync(1) console.log('user1', user1) const user2 = getUserSync(2) console.log('user2', user2) const sum = 1 + 1 console.log(`The sum is ${sum}`) 1 2 3 4 5 6 7 waiting on user1 printing user1 waiting on user2 printing user2 const getUser = require('./get-user') getUser(1, (user1) => { console.log('user1', user1) }) getUser(2, (user2) => { console.log('user2', user2) }) const sum = 1 + 1 console.log(`The sum is ${sum}`) 1 2 3 4 5 6 7 blocking non-blocking
11. BLOCKING VS. NON BLOCKING IO const getUserSync = require('./get-user-sync') const user1 = getUserSync(1) console.log('user1', user1) const user2 = getUserSync(2) console.log('user2', user2) const sum = 1 + 1 console.log(`The sum is ${sum}`) 1 2 3 4 5 6 7 waiting on user1 printing user1 waiting on user2 printing user2 printing sum const getUser = require('./get-user') getUser(1, (user1) => { console.log('user1', user1) }) getUser(2, (user2) => { console.log('user2', user2) }) const sum = 1 + 1 console.log(`The sum is ${sum}`) 1 2 3 4 5 6 7 blocking non-blocking
12. BLOCKING VS. NON BLOCKING IO const getUserSync = require('./get-user-sync') const user1 = getUserSync(1) console.log('user1', user1) const user2 = getUserSync(2) console.log('user2', user2) const sum = 1 + 1 console.log(`The sum is ${sum}`) 1 2 3 4 5 6 7 waiting on user1 printing user1 waiting on user2 printing user2 printing sum const getUser = require('./get-user') getUser(1, (user1) => { console.log('user1', user1) }) getUser(2, (user2) => { console.log('user2', user2) }) const sum = 1 + 1 console.log(`The sum is ${sum}`) 1 2 3 4 5 6 7 starting getUser for user1 blocking non-blocking
13. BLOCKING VS. NON BLOCKING IO const getUserSync = require('./get-user-sync') const user1 = getUserSync(1) console.log('user1', user1) const user2 = getUserSync(2) console.log('user2', user2) const sum = 1 + 1 console.log(`The sum is ${sum}`) 1 2 3 4 5 6 7 waiting on user1 printing user1 waiting on user2 printing user2 printing sum const getUser = require('./get-user') getUser(1, (user1) => { console.log('user1', user1) }) getUser(2, (user2) => { console.log('user2', user2) }) const sum = 1 + 1 console.log(`The sum is ${sum}`) 1 2 3 4 5 6 7 starting getUser for user1 blocking non-blocking starting getUser for user2
14. BLOCKING VS. NON BLOCKING IO const getUserSync = require('./get-user-sync') const user1 = getUserSync(1) console.log('user1', user1) const user2 = getUserSync(2) console.log('user2', user2) const sum = 1 + 1 console.log(`The sum is ${sum}`) 1 2 3 4 5 6 7 waiting on user1 printing user1 waiting on user2 printing user2 printing sum const getUser = require('./get-user') getUser(1, (user1) => { console.log('user1', user1) }) getUser(2, (user2) => { console.log('user2', user2) }) const sum = 1 + 1 console.log(`The sum is ${sum}`) 1 2 3 4 5 6 7 starting getUser for user1 printing sum blocking non-blocking starting getUser for user2
15. BLOCKING VS. NON BLOCKING IO const getUserSync = require('./get-user-sync') const user1 = getUserSync(1) console.log('user1', user1) const user2 = getUserSync(2) console.log('user2', user2) const sum = 1 + 1 console.log(`The sum is ${sum}`) 1 2 3 4 5 6 7 waiting on user1 printing user1 waiting on user2 printing user2 printing sum const getUser = require('./get-user') getUser(1, (user1) => { console.log('user1', user1) }) getUser(2, (user2) => { console.log('user2', user2) }) const sum = 1 + 1 console.log(`The sum is ${sum}`) 1 2 3 4 5 6 7 starting getUser for user1 printing sum blocking non-blocking starting getUser for user2 printing user1
16. BLOCKING VS. NON BLOCKING IO const getUserSync = require('./get-user-sync') const user1 = getUserSync(1) console.log('user1', user1) const user2 = getUserSync(2) console.log('user2', user2) const sum = 1 + 1 console.log(`The sum is ${sum}`) 1 2 3 4 5 6 7 waiting on user1 printing user1 waiting on user2 printing user2 printing sum const getUser = require('./get-user') getUser(1, (user1) => { console.log('user1', user1) }) getUser(2, (user2) => { console.log('user2', user2) }) const sum = 1 + 1 console.log(`The sum is ${sum}`) 1 2 3 4 5 6 7 starting getUser for user1 printing sum blocking non-blocking starting getUser for user2 printing user1 printing user2
17. ARCHITECTURE Node.js Core Library (JavaScript) Node.js Bindings(C/C++) Addons V8 Addons LIBUV C-ARES CRYPTO HTTP ZLIB
18. V8 JS engine built by Google Open source Written in C++ Client (Google Chrome) & Server (Node.js) Compiles JS to machine code Has two compilers JS Code JIT Compiler Inline caches Optimisation compiler Machine Code
19. EVENT LOOP Event Queue Event Loop Worker Threads Register Callback Operation Complete Trigger Callback File System Network Processes HTTP Request Read File (Single Thread) Read Stream
20. EVENTS Object (emitter) function (listener) event
21. EVENTS Object (emitter) function (listener) event callback
22. EVENTS Object (emitter) function (listener) Many objects in Node emit events event callback
23. EVENTS Object (emitter) function (listener) Many objects in Node emit events event callback net.Server request EventEmitter fs.readStream data EventEmitter
24. EVENTS - BASIC EXAMPLE “someone read this file!” “I’m reading…” “I’m done reading, someone print it!” emitter.emit('startRead','/etc/hosts') emitter.on('startRead', (file) => {...} emitter.emit('printContent', data) emitter.on('printContent', (data) => {...} // require the EventEmitter from the events module const EventEmitter = require('events').EventEmitter const fs = require('fs') // create an instance of the EventEmitter object const emitter = new EventEmitter() emitter.on('startRead', (file) => { console.log('Started Reading file...\n') fs.readFile(file, 'utf8', (err, data) => { if (err) { emitter.emit('error', 'from_read') } else{ console.log('Done Reading file...\n') emitter.emit('printContent', data) } }) }) emitter.on('printContent', (data) => { console.log('Printing content of file...\n') console.log(data) emitter.emit('done') }) emitter.on('error', (type) => { console.log(`Faced error while ${type}`) emitter.emit('done') }) emitter.on('done', () => { console.log('Ok its done !') }) emitter.emit('startRead', '/etc/hosts')
25. EVENTS - BASIC EXAMPLE “someone read this file!” “I’m reading…” “I’m done reading, someone print it!” emitter.emit('startRead','/etc/hosts') emitter.on('startRead', (file) => {...} emitter.emit('printContent', data) emitter.on('printContent', (data) => {...} // require the EventEmitter from the events module const EventEmitter = require('events').EventEmitter const fs = require('fs') // create an instance of the EventEmitter object const emitter = new EventEmitter() emitter.on('startRead', (file) => { console.log('Started Reading file...\n') fs.readFile(file, 'utf8', (err, data) => { if (err) { emitter.emit('error', 'from_read') } else{ console.log('Done Reading file...\n') emitter.emit('printContent', data) } }) }) emitter.on('printContent', (data) => { console.log('Printing content of file...\n') console.log(data) emitter.emit('done') }) emitter.on('error', (type) => { console.log(`Faced error while ${type}`) emitter.emit('done') }) emitter.on('done', () => { console.log('Ok its done !') }) emitter.emit('startRead', '/etc/hosts')
26. EVENTS - BASIC EXAMPLE “someone read this file!” “I’m reading…” “I’m done reading, someone print it!” emitter.emit('startRead','/etc/hosts') emitter.on('startRead', (file) => {...} emitter.emit('printContent', data) emitter.on('printContent', (data) => {...} // require the EventEmitter from the events module const EventEmitter = require('events').EventEmitter const fs = require('fs') // create an instance of the EventEmitter object const emitter = new EventEmitter() emitter.on('startRead', (file) => { console.log('Started Reading file...\n') fs.readFile(file, 'utf8', (err, data) => { if (err) { emitter.emit('error', 'from_read') } else{ console.log('Done Reading file...\n') emitter.emit('printContent', data) } }) }) emitter.on('printContent', (data) => { console.log('Printing content of file...\n') console.log(data) emitter.emit('done') }) emitter.on('error', (type) => { console.log(`Faced error while ${type}`) emitter.emit('done') }) emitter.on('done', () => { console.log('Ok its done !') }) emitter.emit('startRead', '/etc/hosts')
27. EVENTS - BASIC EXAMPLE “someone read this file!” “I’m reading…” “I’m done reading, someone print it!” emitter.emit('startRead','/etc/hosts') emitter.on('startRead', (file) => {...} emitter.emit('printContent', data) emitter.on('printContent', (data) => {...} // require the EventEmitter from the events module const EventEmitter = require('events').EventEmitter const fs = require('fs') // create an instance of the EventEmitter object const emitter = new EventEmitter() emitter.on('startRead', (file) => { console.log('Started Reading file...\n') fs.readFile(file, 'utf8', (err, data) => { if (err) { emitter.emit('error', 'from_read') } else{ console.log('Done Reading file...\n') emitter.emit('printContent', data) } }) }) emitter.on('printContent', (data) => { console.log('Printing content of file...\n') console.log(data) emitter.emit('done') }) emitter.on('error', (type) => { console.log(`Faced error while ${type}`) emitter.emit('done') }) emitter.on('done', () => { console.log('Ok its done !') }) emitter.emit('startRead', '/etc/hosts')
28. EVENTS - BASIC EXAMPLE “someone read this file!” “I’m reading…” “I’m done reading, someone print it!” emitter.emit('startRead','/etc/hosts') emitter.on('startRead', (file) => {...} emitter.emit('printContent', data) emitter.on('printContent', (data) => {...} // require the EventEmitter from the events module const EventEmitter = require('events').EventEmitter const fs = require('fs') // create an instance of the EventEmitter object const emitter = new EventEmitter() emitter.on('startRead', (file) => { console.log('Started Reading file...\n') fs.readFile(file, 'utf8', (err, data) => { if (err) { emitter.emit('error', 'from_read') } else{ console.log('Done Reading file...\n') emitter.emit('printContent', data) } }) }) emitter.on('printContent', (data) => { console.log('Printing content of file...\n') console.log(data) emitter.emit('done') }) emitter.on('error', (type) => { console.log(`Faced error while ${type}`) emitter.emit('done') }) emitter.on('done', () => { console.log('Ok its done !') }) emitter.emit('startRead', '/etc/hosts')
29. EVENTS - BASIC EXAMPLE “someone read this file!” “I’m reading…” “I’m done reading, someone print it!” emitter.emit('startRead','/etc/hosts') emitter.on('startRead', (file) => {...} emitter.emit('printContent', data) emitter.on('printContent', (data) => {...} // require the EventEmitter from the events module const EventEmitter = require('events').EventEmitter const fs = require('fs') // create an instance of the EventEmitter object const emitter = new EventEmitter() emitter.on('startRead', (file) => { console.log('Started Reading file...\n') fs.readFile(file, 'utf8', (err, data) => { if (err) { emitter.emit('error', 'from_read') } else{ console.log('Done Reading file...\n') emitter.emit('printContent', data) } }) }) emitter.on('printContent', (data) => { console.log('Printing content of file...\n') console.log(data) emitter.emit('done') }) emitter.on('error', (type) => { console.log(`Faced error while ${type}`) emitter.emit('done') }) emitter.on('done', () => { console.log('Ok its done !') }) emitter.emit('startRead', '/etc/hosts')
30. EVENTS - BASIC EXAMPLE “someone read this file!” “I’m reading…” “I’m done reading, someone print it!” emitter.emit('startRead','/etc/hosts') emitter.on('startRead', (file) => {...} emitter.emit('printContent', data) emitter.on('printContent', (data) => {...} // require the EventEmitter from the events module const EventEmitter = require('events').EventEmitter const fs = require('fs') // create an instance of the EventEmitter object const emitter = new EventEmitter() emitter.on('startRead', (file) => { console.log('Started Reading file...\n') fs.readFile(file, 'utf8', (err, data) => { if (err) { emitter.emit('error', 'from_read') } else{ console.log('Done Reading file...\n') emitter.emit('printContent', data) } }) }) emitter.on('printContent', (data) => { console.log('Printing content of file...\n') console.log(data) emitter.emit('done') }) emitter.on('error', (type) => { console.log(`Faced error while ${type}`) emitter.emit('done') }) emitter.on('done', () => { console.log('Ok its done !') }) emitter.emit('startRead', '/etc/hosts')
31. EVENTS - EXTENDING EVENT EMITTER const EventEmitter = require('events') class RickAndMorty extends EventEmitter { constructor () { super() this.id = 0 this.episodes = [] } save (obj) { obj.id = this.id++ this.episodes.push(obj) this.emit('savedEpisode', obj) } } const rickAndMorty = new RickAndMorty() rickAndMorty.on('savedEpisode', (episode) => { console.log(`saved: ${episode.name} (${episode.code})`) }) rickAndMorty.save({ code: 's01e07', name: 'Raising Gazorpazorp' }) rickAndMorty.save({ code: 's02e06', name: 'The Ricks Must Be Crazy' })
32. EVENTS - EXTENDING EVENT EMITTER const EventEmitter = require('events') class RickAndMorty extends EventEmitter { constructor () { super() this.id = 0 this.episodes = [] } save (obj) { obj.id = this.id++ this.episodes.push(obj) this.emit('savedEpisode', obj) } } const rickAndMorty = new RickAndMorty() rickAndMorty.on('savedEpisode', (episode) => { console.log(`saved: ${episode.name} (${episode.code})`) }) rickAndMorty.save({ code: 's01e07', name: 'Raising Gazorpazorp' }) rickAndMorty.save({ code: 's02e06', name: 'The Ricks Must Be Crazy' })
33. EVENTS - EXTENDING EVENT EMITTER const EventEmitter = require('events') class RickAndMorty extends EventEmitter { constructor () { super() this.id = 0 this.episodes = [] } save (obj) { obj.id = this.id++ this.episodes.push(obj) this.emit('savedEpisode', obj) } } const rickAndMorty = new RickAndMorty() rickAndMorty.on('savedEpisode', (episode) => { console.log(`saved: ${episode.name} (${episode.code})`) }) rickAndMorty.save({ code: 's01e07', name: 'Raising Gazorpazorp' }) rickAndMorty.save({ code: 's02e06', name: 'The Ricks Must Be Crazy' })
34. EVENTS - EXTENDING EVENT EMITTER const EventEmitter = require('events') class RickAndMorty extends EventEmitter { constructor () { super() this.id = 0 this.episodes = [] } save (obj) { obj.id = this.id++ this.episodes.push(obj) this.emit('savedEpisode', obj) } } const rickAndMorty = new RickAndMorty() rickAndMorty.on('savedEpisode', (episode) => { console.log(`saved: ${episode.name} (${episode.code})`) }) rickAndMorty.save({ code: 's01e07', name: 'Raising Gazorpazorp' }) rickAndMorty.save({ code: 's02e06', name: 'The Ricks Must Be Crazy' })
35. EVENTS - EXTENDING EVENT EMITTER const EventEmitter = require('events') class RickAndMorty extends EventEmitter { constructor () { super() this.id = 0 this.episodes = [] } save (obj) { obj.id = this.id++ this.episodes.push(obj) this.emit('savedEpisode', obj) } } const rickAndMorty = new RickAndMorty() rickAndMorty.on('savedEpisode', (episode) => { console.log(`saved: ${episode.name} (${episode.code})`) }) rickAndMorty.save({ code: 's01e07', name: 'Raising Gazorpazorp' }) rickAndMorty.save({ code: 's02e06', name: 'The Ricks Must Be Crazy' })
36. EVENTS - API Listen once Multiple listeners on the same event Set/Get max listeners Prepend listeners Count listeners Get all listeners event names Error event - best practice, always assign listener for `error` event https://nodejs.org/api/events.html
37. STREAMS source destination A way to read and write data in pieces (chunks) buffer
38. STREAMS source destination A way to read and write data in pieces (chunks) buffer readable HTTP request(server) HTTP response(client) fs.createReadStream(src file) process.stdin
39. STREAMS source destination A way to read and write data in pieces (chunks) buffer readable HTTP request(server) HTTP response(client) fs.createReadStream(src file) process.stdin writable HTTP request(client) HTTP response(server) fs.createWriteStream(dest file) process.stdout
40. STREAMS source destination A way to read and write data in pieces (chunks) buffer readable HTTP request(server) HTTP response(client) fs.createReadStream(src file) process.stdin writable HTTP request(client) HTTP response(server) fs.createWriteStream(dest file) process.stdout duplex and transform encoding/decoding(crypto) compress/decompress(zlib) filtering data transforming data net.Socket read write your code external duplex transform your code write transform read or read transform write
41. STREAMS - PIPE A function that takes a readable stream(source) and hooks the output to a writable stream(destination) source.pipe(destination)
42. STREAMS - PIPE A function that takes a readable stream(source) and hooks the output to a writable stream(destination) source.pipe(destination) .pipe(destination) returns destination so we can chain multiple .pipe calls together
43. STREAMS - PIPE A function that takes a readable stream(source) and hooks the output to a writable stream(destination) source.pipe(destination) .pipe(destination) returns destination so we can chain multiple .pipe calls together a.pipe(b).pipe(c).pipe(d)
44. STREAMS - PIPE A function that takes a readable stream(source) and hooks the output to a writable stream(destination) source.pipe(destination) .pipe(destination) returns destination so we can chain multiple .pipe calls together a.pipe(b).pipe(c).pipe(d) kinda like on the commend line
45. STREAMS - PIPE A function that takes a readable stream(source) and hooks the output to a writable stream(destination) source.pipe(destination) .pipe(destination) returns destination so we can chain multiple .pipe calls together a.pipe(b).pipe(c).pipe(d) kinda like on the commend line a | b | c | d
46. STREAMS - PIPE A function that takes a readable stream(source) and hooks the output to a writable stream(destination) source.pipe(destination) .pipe(destination) returns destination so we can chain multiple .pipe calls together a.pipe(b).pipe(c).pipe(d) kinda like on the commend line a | b | c | d const fs = require('fs') const zlib = require('zlib') const r = fs.createReadStream('data.csv') const z = zlib.createGzip() const w = fs.createWriteStream('data.csv.gz') r.pipe(z).pipe(w)
47. STREAMS - WHY YOU SHOULD USE THEM const http = require('http') const fs = require('fs') const server = http.createServer((req, res) => { fs.readFile(__dirname + '/data.csv', (err, data) => { res.end(data) }) }) server.listen(4433)
48. STREAMS - WHY YOU SHOULD USE THEM const http = require('http') const fs = require('fs') const server = http.createServer((req, res) => { fs.readFile(__dirname + '/data.csv', (err, data) => { res.end(data) }) }) server.listen(4433) buffers up the entire file into memory before writing back the result to clients 1. high memory usage 2. bad user experience
49. STREAMS - WHY YOU SHOULD USE THEM const http = require('http') const fs = require('fs') const server = http.createServer((req, res) => { fs.readFile(__dirname + '/data.csv', (err, data) => { res.end(data) }) }) server.listen(4433) buffers up the entire file into memory before writing back the result to clients 1. high memory usage 2. bad user experience const server = http.createServer((req, res) => { const stream = fs.createReadStream(__dirname + '/data.csv') stream.pipe(res) }) better
50. STREAMS - WHY YOU SHOULD USE THEM const http = require('http') const fs = require('fs') const server = http.createServer((req, res) => { fs.readFile(__dirname + '/data.csv', (err, data) => { res.end(data) }) }) server.listen(4433) buffers up the entire file into memory before writing back the result to clients 1. high memory usage 2. bad user experience const server = http.createServer((req, res) => { const stream = fs.createReadStream(__dirname + '/data.csv') stream.pipe(res) }) better with compression const zlib = require('zlib') const server = http.createServer((req, res) => { const gzip = zlib.createGzip() fs.createReadStream(__dirname + '/data.csv') .pipe(gzip) .pipe(res) })
51. STREAMS - EXAMPLE const fs = require('fs') const Transform = require('stream').Transform const read = fs.createReadStream('characters.txt', 'utf8') const write = fs.createWriteStream('favorite.txt') read.on('data', (data) => { console.log(data) }) read.pipe(process.stdout) class FavoriteChars extends Transform { constructor (options) { super(options) } _transform (chunk, enc, done) { chunk = chunk .toString() .split('\n') .filter(chr => ['Rick', 'Morty'].includes(chr)) .join('\n') this.push(chunk) done() } } read.pipe(new FavoriteChars()).pipe(write)
52. STREAMS - EXAMPLE const fs = require('fs') const Transform = require('stream').Transform const read = fs.createReadStream('characters.txt', 'utf8') const write = fs.createWriteStream('favorite.txt') read.on('data', (data) => { console.log(data) }) read.pipe(process.stdout) class FavoriteChars extends Transform { constructor (options) { super(options) } _transform (chunk, enc, done) { chunk = chunk .toString() .split('\n') .filter(chr => ['Rick', 'Morty'].includes(chr)) .join('\n') this.push(chunk) done() } } read.pipe(new FavoriteChars()).pipe(write)
53. STREAMS - EXAMPLE const fs = require('fs') const Transform = require('stream').Transform const read = fs.createReadStream('characters.txt', 'utf8') const write = fs.createWriteStream('favorite.txt') read.on('data', (data) => { console.log(data) }) read.pipe(process.stdout) class FavoriteChars extends Transform { constructor (options) { super(options) } _transform (chunk, enc, done) { chunk = chunk .toString() .split('\n') .filter(chr => ['Rick', 'Morty'].includes(chr)) .join('\n') this.push(chunk) done() } } read.pipe(new FavoriteChars()).pipe(write)
54. STREAMS - EXAMPLE const fs = require('fs') const Transform = require('stream').Transform const read = fs.createReadStream('characters.txt', 'utf8') const write = fs.createWriteStream('favorite.txt') read.on('data', (data) => { console.log(data) }) read.pipe(process.stdout) class FavoriteChars extends Transform { constructor (options) { super(options) } _transform (chunk, enc, done) { chunk = chunk .toString() .split('\n') .filter(chr => ['Rick', 'Morty'].includes(chr)) .join('\n') this.push(chunk) done() } } read.pipe(new FavoriteChars()).pipe(write)
55. STREAMS - EXAMPLE const fs = require('fs') const Transform = require('stream').Transform const read = fs.createReadStream('characters.txt', 'utf8') const write = fs.createWriteStream('favorite.txt') read.on('data', (data) => { console.log(data) }) read.pipe(process.stdout) class FavoriteChars extends Transform { constructor (options) { super(options) } _transform (chunk, enc, done) { chunk = chunk .toString() .split('\n') .filter(chr => ['Rick', 'Morty'].includes(chr)) .join('\n') this.push(chunk) done() } } read.pipe(new FavoriteChars()).pipe(write)
56. STREAMS - EXAMPLE const fs = require('fs') const Transform = require('stream').Transform const read = fs.createReadStream('characters.txt', 'utf8') const write = fs.createWriteStream('favorite.txt') read.on('data', (data) => { console.log(data) }) read.pipe(process.stdout) class FavoriteChars extends Transform { constructor (options) { super(options) } _transform (chunk, enc, done) { chunk = chunk .toString() .split('\n') .filter(chr => ['Rick', 'Morty'].includes(chr)) .join('\n') this.push(chunk) done() } } read.pipe(new FavoriteChars()).pipe(write)
57. STREAMS - EXAMPLE const fs = require('fs') const Transform = require('stream').Transform const read = fs.createReadStream('characters.txt', 'utf8') const write = fs.createWriteStream('favorite.txt') read.on('data', (data) => { console.log(data) }) read.pipe(process.stdout) class FavoriteChars extends Transform { constructor (options) { super(options) } _transform (chunk, enc, done) { chunk = chunk .toString() .split('\n') .filter(chr => ['Rick', 'Morty'].includes(chr)) .join('\n') this.push(chunk) done() } } read.pipe(new FavoriteChars()).pipe(write)
58. STREAMS - EXAMPLE const fs = require('fs') const Transform = require('stream').Transform const read = fs.createReadStream('characters.txt', 'utf8') const write = fs.createWriteStream('favorite.txt') read.on('data', (data) => { console.log(data) }) read.pipe(process.stdout) class FavoriteChars extends Transform { constructor (options) { super(options) } _transform (chunk, enc, done) { chunk = chunk .toString() .split('\n') .filter(chr => ['Rick', 'Morty'].includes(chr)) .join('\n') this.push(chunk) done() } } read.pipe(new FavoriteChars()).pipe(write)
59. MODULES Module: A reusable block of code whose existence does not accidentally impact other code CommonJS: An agreed upon standard for how code modules should be structured rick.js morty.js const callRick = () => { console.log('Wubba-lubba-dub-dub!') } module.exports = callRick const callRick = require('./rick') callRick()
60. MODULES Module: A reusable block of code whose existence does not accidentally impact other code CommonJS: An agreed upon standard for how code modules should be structured rick.js morty.js const callRick = () => { console.log('Wubba-lubba-dub-dub!') } module.exports = callRick const callRick = require('./rick') callRick() ?
61. MODULES const callRick = () => { console.log('Wubba-lubba-dub-dub!') } module.exports = callRick
62. (function (exports, require, module, __filename, __dirname) { }); MODULES const callRick = () => { console.log('Wubba-lubba-dub-dub!') } module.exports = callRick
63. (function (exports, require, module, __filename, __dirname) { }); MODULES const callRick = () => { console.log('Wubba-lubba-dub-dub!') } module.exports = callRick fn(module.exports, require, module, filename, dirname)
64. (function (exports, require, module, __filename, __dirname) { }); MODULES const callRick = () => { console.log('Wubba-lubba-dub-dub!') } module.exports = callRick fn(module.exports, require, module, filename, dirname) return module.exports this is what require returns
65. MODULES - PATTERNS // 0. export all things! module.exports = 1 module.exports = 'R&M' module.exports = {name: 'Rick'} module.exports = ['Rick', 'Morty'] module.exports = new Date() // 1. override module.exports object with function expression module.exports = () => { console.log('Wubba-lubba-dub-dub!') } // 2. assign function expression as method of exports module.exports.callRick = () => { console.log('Wubba-lubba-dub-dub!') } class Rick { constructor () { this.greet = 'Wubba-lubba-dub-dub!' } callRick () { console.log(this.greet) } } // 3. export new class(function) instance module.exports = new Rick() // 4. export class(function) itself module.exports = Rick // 5. export multiple modules in single export const Morty = { callMorty: () => console.log('Oh Geez!') } module.exports = { Rick, Morty } // 0. console.log(require('./rickAndMorty')) // 1 console.log(require('./rickAndMorty')) // 'R&M' console.log(require('./rickAndMorty')) // {name: 'Rick'} console.log(require('./rickAndMorty')) // ['Rick', 'Morty'] console.log(require('./rickAndMorty')).now() // 1495441119790 // 1. const callRick = require('./callRick') callRick() // 2. const callRick = require('./callRick').callRick callRick() // 3. const Rick = require('./rick') Rick.greet = 'shum-shum-schlippety-dop!' Rick.callRick() const Rick = require('./rick') Rick.callRick() // 4. const Rick = require('./rick') const rick = new Rick() rick.callRick() // 5. const rickAndMorty = require('./rickAndMorty') const morty = rickAndMorty.Morty morty.callMorty() const rick = new rickAndMorty.Rick() rick.callRick()
66. MODULES - PATTERNS // 0. export all things! module.exports = 1 module.exports = 'R&M' module.exports = {name: 'Rick'} module.exports = ['Rick', 'Morty'] module.exports = new Date() // 1. override module.exports object with function expression module.exports = () => { console.log('Wubba-lubba-dub-dub!') } // 2. assign function expression as method of exports module.exports.callRick = () => { console.log('Wubba-lubba-dub-dub!') } class Rick { constructor () { this.greet = 'Wubba-lubba-dub-dub!' } callRick () { console.log(this.greet) } } // 3. export new class(function) instance module.exports = new Rick() // 4. export class(function) itself module.exports = Rick // 5. export multiple modules in single export const Morty = { callMorty: () => console.log('Oh Geez!') } module.exports = { Rick, Morty } // 0. console.log(require('./rickAndMorty')) // 1 console.log(require('./rickAndMorty')) // 'R&M' console.log(require('./rickAndMorty')) // {name: 'Rick'} console.log(require('./rickAndMorty')) // ['Rick', 'Morty'] console.log(require('./rickAndMorty')).now() // 1495441119790 // 1. const callRick = require('./callRick') callRick() // 2. const callRick = require('./callRick').callRick callRick() // 3. const Rick = require('./rick') Rick.greet = 'shum-shum-schlippety-dop!' Rick.callRick() const Rick = require('./rick') Rick.callRick() // 4. const Rick = require('./rick') const rick = new Rick() rick.callRick() // 5. const rickAndMorty = require('./rickAndMorty') const morty = rickAndMorty.Morty morty.callMorty() const rick = new rickAndMorty.Rick() rick.callRick()
67. MODULES - PATTERNS // 0. export all things! module.exports = 1 module.exports = 'R&M' module.exports = {name: 'Rick'} module.exports = ['Rick', 'Morty'] module.exports = new Date() // 1. override module.exports object with function expression module.exports = () => { console.log('Wubba-lubba-dub-dub!') } // 2. assign function expression as method of exports module.exports.callRick = () => { console.log('Wubba-lubba-dub-dub!') } class Rick { constructor () { this.greet = 'Wubba-lubba-dub-dub!' } callRick () { console.log(this.greet) } } // 3. export new class(function) instance module.exports = new Rick() // 4. export class(function) itself module.exports = Rick // 5. export multiple modules in single export const Morty = { callMorty: () => console.log('Oh Geez!') } module.exports = { Rick, Morty } // 0. console.log(require('./rickAndMorty')) // 1 console.log(require('./rickAndMorty')) // 'R&M' console.log(require('./rickAndMorty')) // {name: 'Rick'} console.log(require('./rickAndMorty')) // ['Rick', 'Morty'] console.log(require('./rickAndMorty')).now() // 1495441119790 // 1. const callRick = require('./callRick') callRick() // 2. const callRick = require('./callRick').callRick callRick() // 3. const Rick = require('./rick') Rick.greet = 'shum-shum-schlippety-dop!' Rick.callRick() const Rick = require('./rick') Rick.callRick() // 4. const Rick = require('./rick') const rick = new Rick() rick.callRick() // 5. const rickAndMorty = require('./rickAndMorty') const morty = rickAndMorty.Morty morty.callMorty() const rick = new rickAndMorty.Rick() rick.callRick()
68. MODULES - PATTERNS // 0. export all things! module.exports = 1 module.exports = 'R&M' module.exports = {name: 'Rick'} module.exports = ['Rick', 'Morty'] module.exports = new Date() // 1. override module.exports object with function expression module.exports = () => { console.log('Wubba-lubba-dub-dub!') } // 2. assign function expression as method of exports module.exports.callRick = () => { console.log('Wubba-lubba-dub-dub!') } class Rick { constructor () { this.greet = 'Wubba-lubba-dub-dub!' } callRick () { console.log(this.greet) } } // 3. export new class(function) instance module.exports = new Rick() // 4. export class(function) itself module.exports = Rick // 5. export multiple modules in single export const Morty = { callMorty: () => console.log('Oh Geez!') } module.exports = { Rick, Morty } // 0. console.log(require('./rickAndMorty')) // 1 console.log(require('./rickAndMorty')) // 'R&M' console.log(require('./rickAndMorty')) // {name: 'Rick'} console.log(require('./rickAndMorty')) // ['Rick', 'Morty'] console.log(require('./rickAndMorty')).now() // 1495441119790 // 1. const callRick = require('./callRick') callRick() // 2. const callRick = require('./callRick').callRick callRick() // 3. const Rick = require('./rick') Rick.greet = 'shum-shum-schlippety-dop!' Rick.callRick() const Rick = require('./rick') Rick.callRick() // 4. const Rick = require('./rick') const rick = new Rick() rick.callRick() // 5. const rickAndMorty = require('./rickAndMorty') const morty = rickAndMorty.Morty morty.callMorty() const rick = new rickAndMorty.Rick() rick.callRick()
69. MODULES - PATTERNS // 0. export all things! module.exports = 1 module.exports = 'R&M' module.exports = {name: 'Rick'} module.exports = ['Rick', 'Morty'] module.exports = new Date() // 1. override module.exports object with function expression module.exports = () => { console.log('Wubba-lubba-dub-dub!') } // 2. assign function expression as method of exports module.exports.callRick = () => { console.log('Wubba-lubba-dub-dub!') } class Rick { constructor () { this.greet = 'Wubba-lubba-dub-dub!' } callRick () { console.log(this.greet) } } // 3. export new class(function) instance module.exports = new Rick() // 4. export class(function) itself module.exports = Rick // 5. export multiple modules in single export const Morty = { callMorty: () => console.log('Oh Geez!') } module.exports = { Rick, Morty } // 0. console.log(require('./rickAndMorty')) // 1 console.log(require('./rickAndMorty')) // 'R&M' console.log(require('./rickAndMorty')) // {name: 'Rick'} console.log(require('./rickAndMorty')) // ['Rick', 'Morty'] console.log(require('./rickAndMorty')).now() // 1495441119790 // 1. const callRick = require('./callRick') callRick() // 2. const callRick = require('./callRick').callRick callRick() // 3. const Rick = require('./rick') Rick.greet = 'shum-shum-schlippety-dop!' Rick.callRick() const Rick = require('./rick') Rick.callRick() // 4. const Rick = require('./rick') const rick = new Rick() rick.callRick() // 5. const rickAndMorty = require('./rickAndMorty') const morty = rickAndMorty.Morty morty.callMorty() const rick = new rickAndMorty.Rick() rick.callRick()
70. MODULES - PATTERNS // 0. export all things! module.exports = 1 module.exports = 'R&M' module.exports = {name: 'Rick'} module.exports = ['Rick', 'Morty'] module.exports = new Date() // 1. override module.exports object with function expression module.exports = () => { console.log('Wubba-lubba-dub-dub!') } // 2. assign function expression as method of exports module.exports.callRick = () => { console.log('Wubba-lubba-dub-dub!') } class Rick { constructor () { this.greet = 'Wubba-lubba-dub-dub!' } callRick () { console.log(this.greet) } } // 3. export new class(function) instance module.exports = new Rick() // 4. export class(function) itself module.exports = Rick // 5. export multiple modules in single export const Morty = { callMorty: () => console.log('Oh Geez!') } module.exports = { Rick, Morty } // 0. console.log(require('./rickAndMorty')) // 1 console.log(require('./rickAndMorty')) // 'R&M' console.log(require('./rickAndMorty')) // {name: 'Rick'} console.log(require('./rickAndMorty')) // ['Rick', 'Morty'] console.log(require('./rickAndMorty')).now() // 1495441119790 // 1. const callRick = require('./callRick') callRick() // 2. const callRick = require('./callRick').callRick callRick() // 3. const Rick = require('./rick') Rick.greet = 'shum-shum-schlippety-dop!' Rick.callRick() const Rick = require('./rick') Rick.callRick() // 4. const Rick = require('./rick') const rick = new Rick() rick.callRick() // 5. const rickAndMorty = require('./rickAndMorty') const morty = rickAndMorty.Morty morty.callMorty() const rick = new rickAndMorty.Rick() rick.callRick()
71. MODULES - PATTERNS // 0. export all things! module.exports = 1 module.exports = 'R&M' module.exports = {name: 'Rick'} module.exports = ['Rick', 'Morty'] module.exports = new Date() // 1. override module.exports object with function expression module.exports = () => { console.log('Wubba-lubba-dub-dub!') } // 2. assign function expression as method of exports module.exports.callRick = () => { console.log('Wubba-lubba-dub-dub!') } class Rick { constructor () { this.greet = 'Wubba-lubba-dub-dub!' } callRick () { console.log(this.greet) } } // 3. export new class(function) instance module.exports = new Rick() // 4. export class(function) itself module.exports = Rick // 5. export multiple modules in single export const Morty = { callMorty: () => console.log('Oh Geez!') } module.exports = { Rick, Morty } // 0. console.log(require('./rickAndMorty')) // 1 console.log(require('./rickAndMorty')) // 'R&M' console.log(require('./rickAndMorty')) // {name: 'Rick'} console.log(require('./rickAndMorty')) // ['Rick', 'Morty'] console.log(require('./rickAndMorty')).now() // 1495441119790 // 1. const callRick = require('./callRick') callRick() // 2. const callRick = require('./callRick').callRick callRick() // 3. const Rick = require('./rick') Rick.greet = 'shum-shum-schlippety-dop!' Rick.callRick() const Rick = require('./rick') Rick.callRick() // 4. const Rick = require('./rick') const rick = new Rick() rick.callRick() // 5. const rickAndMorty = require('./rickAndMorty') const morty = rickAndMorty.Morty morty.callMorty() const rick = new rickAndMorty.Rick() rick.callRick()
72. MODULES - PATTERNS // 0. export all things! module.exports = 1 module.exports = 'R&M' module.exports = {name: 'Rick'} module.exports = ['Rick', 'Morty'] module.exports = new Date() // 1. override module.exports object with function expression module.exports = () => { console.log('Wubba-lubba-dub-dub!') } // 2. assign function expression as method of exports module.exports.callRick = () => { console.log('Wubba-lubba-dub-dub!') } class Rick { constructor () { this.greet = 'Wubba-lubba-dub-dub!' } callRick () { console.log(this.greet) } } // 3. export new class(function) instance module.exports = new Rick() // 4. export class(function) itself module.exports = Rick // 5. export multiple modules in single export const Morty = { callMorty: () => console.log('Oh Geez!') } module.exports = { Rick, Morty } // 0. console.log(require('./rickAndMorty')) // 1 console.log(require('./rickAndMorty')) // 'R&M' console.log(require('./rickAndMorty')) // {name: 'Rick'} console.log(require('./rickAndMorty')) // ['Rick', 'Morty'] console.log(require('./rickAndMorty')).now() // 1495441119790 // 1. const callRick = require('./callRick') callRick() // 2. const callRick = require('./callRick').callRick callRick() // 3. const Rick = require('./rick') Rick.greet = 'shum-shum-schlippety-dop!' Rick.callRick() const Rick = require('./rick') Rick.callRick() // 4. const Rick = require('./rick') const rick = new Rick() rick.callRick() // 5. const rickAndMorty = require('./rickAndMorty') const morty = rickAndMorty.Morty morty.callMorty() const rick = new rickAndMorty.Rick() rick.callRick()
73. MODULES - PATTERNS // 0. export all things! module.exports = 1 module.exports = 'R&M' module.exports = {name: 'Rick'} module.exports = ['Rick', 'Morty'] module.exports = new Date() // 1. override module.exports object with function expression module.exports = () => { console.log('Wubba-lubba-dub-dub!') } // 2. assign function expression as method of exports module.exports.callRick = () => { console.log('Wubba-lubba-dub-dub!') } class Rick { constructor () { this.greet = 'Wubba-lubba-dub-dub!' } callRick () { console.log(this.greet) } } // 3. export new class(function) instance module.exports = new Rick() // 4. export class(function) itself module.exports = Rick // 5. export multiple modules in single export const Morty = { callMorty: () => console.log('Oh Geez!') } module.exports = { Rick, Morty } // 0. console.log(require('./rickAndMorty')) // 1 console.log(require('./rickAndMorty')) // 'R&M' console.log(require('./rickAndMorty')) // {name: 'Rick'} console.log(require('./rickAndMorty')) // ['Rick', 'Morty'] console.log(require('./rickAndMorty')).now() // 1495441119790 // 1. const callRick = require('./callRick') callRick() // 2. const callRick = require('./callRick').callRick callRick() // 3. const Rick = require('./rick') Rick.greet = 'shum-shum-schlippety-dop!' Rick.callRick() const Rick = require('./rick') Rick.callRick() // 4. const Rick = require('./rick') const rick = new Rick() rick.callRick() // 5. const rickAndMorty = require('./rickAndMorty') const morty = rickAndMorty.Morty morty.callMorty() const rick = new rickAndMorty.Rick() rick.callRick()
74. MODULES - PATTERNS // 0. export all things! module.exports = 1 module.exports = 'R&M' module.exports = {name: 'Rick'} module.exports = ['Rick', 'Morty'] module.exports = new Date() // 1. override module.exports object with function expression module.exports = () => { console.log('Wubba-lubba-dub-dub!') } // 2. assign function expression as method of exports module.exports.callRick = () => { console.log('Wubba-lubba-dub-dub!') } class Rick { constructor () { this.greet = 'Wubba-lubba-dub-dub!' } callRick () { console.log(this.greet) } } // 3. export new class(function) instance module.exports = new Rick() // 4. export class(function) itself module.exports = Rick // 5. export multiple modules in single export const Morty = { callMorty: () => console.log('Oh Geez!') } module.exports = { Rick, Morty } // 0. console.log(require('./rickAndMorty')) // 1 console.log(require('./rickAndMorty')) // 'R&M' console.log(require('./rickAndMorty')) // {name: 'Rick'} console.log(require('./rickAndMorty')) // ['Rick', 'Morty'] console.log(require('./rickAndMorty')).now() // 1495441119790 // 1. const callRick = require('./callRick') callRick() // 2. const callRick = require('./callRick').callRick callRick() // 3. const Rick = require('./rick') Rick.greet = 'shum-shum-schlippety-dop!' Rick.callRick() const Rick = require('./rick') Rick.callRick() // 4. const Rick = require('./rick') const rick = new Rick() rick.callRick() // 5. const rickAndMorty = require('./rickAndMorty') const morty = rickAndMorty.Morty morty.callMorty() const rick = new rickAndMorty.Rick() rick.callRick()
75. MODULES - PATTERNS // 0. export all things! module.exports = 1 module.exports = 'R&M' module.exports = {name: 'Rick'} module.exports = ['Rick', 'Morty'] module.exports = new Date() // 1. override module.exports object with function expression module.exports = () => { console.log('Wubba-lubba-dub-dub!') } // 2. assign function expression as method of exports module.exports.callRick = () => { console.log('Wubba-lubba-dub-dub!') } class Rick { constructor () { this.greet = 'Wubba-lubba-dub-dub!' } callRick () { console.log(this.greet) } } // 3. export new class(function) instance module.exports = new Rick() // 4. export class(function) itself module.exports = Rick // 5. export multiple modules in single export const Morty = { callMorty: () => console.log('Oh Geez!') } module.exports = { Rick, Morty } // 0. console.log(require('./rickAndMorty')) // 1 console.log(require('./rickAndMorty')) // 'R&M' console.log(require('./rickAndMorty')) // {name: 'Rick'} console.log(require('./rickAndMorty')) // ['Rick', 'Morty'] console.log(require('./rickAndMorty')).now() // 1495441119790 // 1. const callRick = require('./callRick') callRick() // 2. const callRick = require('./callRick').callRick callRick() // 3. const Rick = require('./rick') Rick.greet = 'shum-shum-schlippety-dop!' Rick.callRick() const Rick = require('./rick') Rick.callRick() // 4. const Rick = require('./rick') const rick = new Rick() rick.callRick() // 5. const rickAndMorty = require('./rickAndMorty') const morty = rickAndMorty.Morty morty.callMorty() const rick = new rickAndMorty.Rick() rick.callRick()
76. MODULES - EXPORTS VS MODULE.EXPORTS (function (exports, require, module, __filename, __dirname) { // your code here…. }); fn(module.exports, require, module, filename, dirname)
77. MODULES - EXPORTS VS MODULE.EXPORTS (function (exports, require, module, __filename, __dirname) { // your code here…. }); fn(module.exports, require, module, filename, dirname) exports.callRick = () => { console.log('Wubba-lubba-dub-dub!') } console.log(exports) // { callRick: [Function] } console.log(module.exports) // { callRick: [Function] }
78. MODULES - EXPORTS VS MODULE.EXPORTS (function (exports, require, module, __filename, __dirname) { // your code here…. }); fn(module.exports, require, module, filename, dirname) exports.callRick = () => { console.log('Wubba-lubba-dub-dub!') } console.log(exports) // { callRick: [Function] } console.log(module.exports) // { callRick: [Function] } exports module.exports alias {}
79. MODULES - EXPORTS VS MODULE.EXPORTS (function (exports, require, module, __filename, __dirname) { // your code here…. }); fn(module.exports, require, module, filename, dirname) exports.callRick = () => { console.log('Wubba-lubba-dub-dub!') } console.log(exports) // { callRick: [Function] } console.log(module.exports) // { callRick: [Function] } exports = () => { console.log('Wubba-lubba-dub-dub!') } console.log(exports) // [Function] console.log(module.exports) // {} Be careful exports module.exports alias {}
80. MODULES - EXPORTS VS MODULE.EXPORTS (function (exports, require, module, __filename, __dirname) { // your code here…. }); fn(module.exports, require, module, filename, dirname) exports.callRick = () => { console.log('Wubba-lubba-dub-dub!') } console.log(exports) // { callRick: [Function] } console.log(module.exports) // { callRick: [Function] } exports = () => { console.log('Wubba-lubba-dub-dub!') } console.log(exports) // [Function] console.log(module.exports) // {} Be careful Error: callRick is not a function exports module.exports alias {}
81. MODULES - EXPORTS VS MODULE.EXPORTS (function (exports, require, module, __filename, __dirname) { // your code here…. }); fn(module.exports, require, module, filename, dirname) exports.callRick = () => { console.log('Wubba-lubba-dub-dub!') } console.log(exports) // { callRick: [Function] } console.log(module.exports) // { callRick: [Function] } exports = () => { console.log('Wubba-lubba-dub-dub!') } console.log(exports) // [Function] console.log(module.exports) // {} Be careful Error: callRick is not a function module.exports exports by reference Object exports module.exports alias {}
82. MODULES - EXPORTS VS MODULE.EXPORTS (function (exports, require, module, __filename, __dirname) { // your code here…. }); fn(module.exports, require, module, filename, dirname) exports.callRick = () => { console.log('Wubba-lubba-dub-dub!') } console.log(exports) // { callRick: [Function] } console.log(module.exports) // { callRick: [Function] } exports = () => { console.log('Wubba-lubba-dub-dub!') } console.log(exports) // [Function] console.log(module.exports) // {} Be careful Error: callRick is not a function module.exports exports by reference Object module.exports exports Object Object = exports module.exports alias {}
83. MODULES - REQUIRE ALL TOGETHER require(X) from module at path Y 1. If X is a core module, a. return the core module b. STOP 2. If X begins with '/' a. set Y to be the filesystem root 3. If X begins with './' or '/' or '../' a. LOAD_AS_FILE(Y + X) b. LOAD_AS_DIRECTORY(Y + X) 4. LOAD_NODE_MODULES(X, dirname(Y)) 5. THROW "not found" LOAD_AS_FILE(X) 1. If X is a file, load X as JavaScript text. STOP 2. If X.js is a file, load X.js as JavaScript text. STOP 3. If X.json is a file, parse X.json to a JavaScript Object. STOP 4. If X.node is a file, load X.node as binary addon. STOP LOAD_INDEX(X) 1. If X/index.js is a file, load X/index.js as JavaScript text. STOP 2. If X/index.json is a file, parse X/index.json to a JavaScript object. STOP 3. If X/index.node is a file, load X/index.node as binary addon. STOP LOAD_AS_DIRECTORY(X) 1. If X/package.json is a file, a. Parse X/package.json, and look for "main" field. b. let M = X + (json main field) c. LOAD_AS_FILE(M) d. LOAD_INDEX(M) 2. LOAD_INDEX(X) LOAD_NODE_MODULES(X, START) 1. let DIRS=NODE_MODULES_PATHS(START) 2. for each DIR in DIRS: a. LOAD_AS_FILE(DIR/X) b. LOAD_AS_DIRECTORY(DIR/X) NODE_MODULES_PATHS(START) 1. let PARTS = path split(START) 2. let I = count of PARTS - 1 3. let DIRS = [] 4. while I >= 0, a. if PARTS[I] = "node_modules" CONTINUE b. DIR = path join(PARTS[0 .. I] + "node_modules") c. DIRS = DIRS + DIR d. let I = I - 1 5. return DIRS
84. NPM - GLOSSARY NPM - Node Package Manager, comes with node by default Package - Code managed and maintain by package management system Package Management System - Software that automates installing and updating packages, deals with what version you have or need, and manages dependencies Dependency - Code that another set of code depends on to function node_modules - A folder in your project root that contains all installed packages and dependencies package.json - A file contains meta data about your app or module. includes the list of dependencies to install from NPM when running `npm install` Yarn - A client built on top of NPM, keeps consistency across all installations by adding yarn.lock file, faster than NPM (comparing to v4)
85. NPM - INSTALL
86. NPM - INSTALL Create initial package.json $ npm init -y
87. NPM - INSTALL Create initial package.json $ npm init -y $ npm install something Install Installs into local node_modules directory In your project root (ex. /Home/myApp) Home / myApp / node_modules / something
88. NPM - INSTALL Create initial package.json $ npm init -y $ npm install something Install Installs into local node_modules directory In your project root (ex. /Home/myApp) Home / myApp / node_modules / something $ npm install -g something install globally (use case for executables)
89. NPM - INSTALL Create initial package.json $ npm init -y $ npm install something Install Installs into local node_modules directory In your project root (ex. /Home/myApp) Home / myApp / node_modules / something In /Users/ofer/myApp/app.js const something = require('something') • /Users/ofer/myApp/node_modules/something.js • /Users/ofer/node_modules/something.js • /Users/node_modules/something.js • /node_modules/something.js $ npm install -g something install globally (use case for executables)
90. NPM - PACKAGE.JSON { "name": "nodejs-course-2017", "version": "1.0.0", "description": "code examples and exercises for node.js course", "main": "index.js", "scripts": { "test": "echo \"Error: no test specified\" && exit 1" }, "repository": { "type": "git", "url": "git+https://github.com/xl8/nodejs-course-2017.git" }, "keywords": [], "author": "ofer.itzhaki@nielsen.com", "license": "MIT", "bugs": { "url": "https://github.com/xl8/nodejs-course-2017/issues" }, "homepage": "https://github.com/xl8/nodejs-course-2017#readme", "dependencies": { "express": "^4.15.3" } } version number
91. NPM - SEMANTIC VERSIONING "express": "^4.15.3" 4 15 3 major minor patch major minor patch caret(^) tilde(~) - breaking change - backwards compatible new functionality - old functionality deprecated, but operational - large internal refactor - bug fix 4.*.* 4.15.*
92. EXPRESS "a minimal and flexible node.js web application framework"
93. EXPRESS "a minimal and flexible node.js web application framework" const http = require('http') http.createServer((req, res) => { // Homepage if (req.url === '/') { res.writeHead(200, { 'Content-Type': 'text/html' }) res.end('Welcome to the homepage!') } // About page else if (req.url === '/about') { res.writeHead(200, { 'Content-Type': 'text/html' }) res.end('Welcome to the about page!') } // 404 else { res.writeHead(404, { 'Content-Type': 'text/plain' }) res.end('404 error! File not found.') } }).listen(1337, 'localhost')
94. EXPRESS "a minimal and flexible node.js web application framework" const express = require('express') const app = express() // Homepage app.get('/', (req, res) => { res.status(200).send('Welcome to the homepage!') }) // About page app.get('/about', (req, res) => { res.status(200).send('Welcome to the about page!') }) // 404 app.get('/*', (req, res) => { res.status(404).send('404 error! File not found.') }) app.listen(1337) const http = require('http') http.createServer((req, res) => { // Homepage if (req.url === '/') { res.writeHead(200, { 'Content-Type': 'text/html' }) res.end('Welcome to the homepage!') } // About page else if (req.url === '/about') { res.writeHead(200, { 'Content-Type': 'text/html' }) res.end('Welcome to the about page!') } // 404 else { res.writeHead(404, { 'Content-Type': 'text/plain' }) res.end('404 error! File not found.') } }).listen(1337, 'localhost')
95. EXPRESS Client Server socket HTTP Request HTTP Response 199.203.181.36 64.233.163.104 Basics reminder: TCP/IP Client-Server Model port: 80 443
96. EXPRESS Client Server socket HTTP Request HTTP Response 199.203.181.36 64.233.163.104 Basics reminder: TCP/IP Client-Server Model Node.js HTTP module Request Express Response port: 80 443
97. EXPRESS Client Server socket HTTP Request HTTP Response 199.203.181.36 64.233.163.104 Basics reminder: TCP/IP Client-Server Model {Request} {Response} Next() Node.js HTTP module Request Express Response port: 80 443
98. EXPRESS Client Server socket HTTP Request HTTP Response 199.203.181.36 64.233.163.104 Basics reminder: TCP/IP Client-Server Model {Request} {Response} Next() Middleware body parser Node.js HTTP module Request Express Response port: 80 443
99. EXPRESS Client Server socket HTTP Request HTTP Response 199.203.181.36 64.233.163.104 Basics reminder: TCP/IP Client-Server Model {Request} {Response} Next() next cookie parser Middleware body parser Node.js HTTP module Request Express Response port: 80 443
100. EXPRESS Client Server socket HTTP Request HTTP Response 199.203.181.36 64.233.163.104 Basics reminder: TCP/IP Client-Server Model {Request} {Response} Next() next cookie parser Middleware body parser logger next Node.js HTTP module Request Express Response port: 80 443
101. EXPRESS Client Server socket HTTP Request HTTP Response 199.203.181.36 64.233.163.104 Basics reminder: TCP/IP Client-Server Model {Request} {Response} Next() next cookie parser Routes next Router Middleware body parser logger next Node.js HTTP module Request Express Response port: 80 443
102. EXPRESS Client Server socket HTTP Request HTTP Response 199.203.181.36 64.233.163.104 Basics reminder: TCP/IP Client-Server Model {Request} {Response} Next() next cookie parser Routes next Router multer /upload Middleware body parser logger next Node.js HTTP module Request Express Response port: 80 443
103. EXPRESS Client Server socket HTTP Request HTTP Response 199.203.181.36 64.233.163.104 Basics reminder: TCP/IP Client-Server Model {Request} {Response} Next() next cookie parser Routes next Router multer /upload next request handler Middleware body parser logger next Node.js HTTP module Request Express Response port: 80 443
104. EXPRESS Client Server socket HTTP Request HTTP Response 199.203.181.36 64.233.163.104 Basics reminder: TCP/IP Client-Server Model {Request} {Response} Next() next cookie parser Routes next Router multer /upload next request handler Middleware body parser logger next Node.js HTTP module Request Express Response error handling MW err port: 80 443
105. EXPRESS Demo let’s build an app!