K Y I V 2 0 1 9 Luciano Mammino (@loige) IT’S ABOUT TIME TO IT’S ABOUT TIME TO EMBRACE STREAMS EMBRACE STREAMS loige.link/streams-kyiv May 18th 1

// buffer-copy.js const { readFileSync, writeFileSync } = require('fs') const [,, src, dest] = process.argv // read entire file content const content = readFileSync(src) // write that content somewhere else writeFileSync(dest, content) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 @loige 2

// buffer-copy.js const { readFileSync, writeFileSync } = require('fs') const [,, src, dest] = process.argv // read entire file content const content = readFileSync(src) // write that content somewhere else writeFileSync(dest, content) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 const { readFileSync, writeFileSync } = require('fs') // buffer-copy.js 1 2 3 4 5 6 7 const [,, src, dest] = process.argv 8 9 // read entire file content 10 const content = readFileSync(src) 11 12 // write that content somewhere else 13 writeFileSync(dest, content) 14 @loige 2

// buffer-copy.js const { readFileSync, writeFileSync } = require('fs') const [,, src, dest] = process.argv // read entire file content const content = readFileSync(src) // write that content somewhere else writeFileSync(dest, content) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 const { readFileSync, writeFileSync } = require('fs') // buffer-copy.js 1 2 3 4 5 6 7 const [,, src, dest] = process.argv 8 9 // read entire file content 10 const content = readFileSync(src) 11 12 // write that content somewhere else 13 writeFileSync(dest, content) 14 // read entire file content const content = readFileSync(src) // buffer-copy.js 1 2 const { 3 readFileSync, 4 writeFileSync 5 } = require('fs') 6 7 const [,, src, dest] = process.argv 8 9 10 11 12 // write that content somewhere else 13 writeFileSync(dest, content) 14 @loige 2

// buffer-copy.js const { readFileSync, writeFileSync } = require('fs') const [,, src, dest] = process.argv // read entire file content const content = readFileSync(src) // write that content somewhere else writeFileSync(dest, content) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 const { readFileSync, writeFileSync } = require('fs') // buffer-copy.js 1 2 3 4 5 6 7 const [,, src, dest] = process.argv 8 9 // read entire file content 10 const content = readFileSync(src) 11 12 // write that content somewhere else 13 writeFileSync(dest, content) 14 // read entire file content const content = readFileSync(src) // buffer-copy.js 1 2 const { 3 readFileSync, 4 writeFileSync 5 } = require('fs') 6 7 const [,, src, dest] = process.argv 8 9 10 11 12 // write that content somewhere else 13 writeFileSync(dest, content) 14 // write that content somewhere else writeFileSync(dest, content) // buffer-copy.js 1 2 const { 3 readFileSync, 4 writeFileSync 5 } = require('fs') 6 7 const [,, src, dest] = process.argv 8 9 // read entire file content 10 const content = readFileSync(src) 11 12 13 14 @loige 2

@loige 3

WE DO THIS ALL THE TIME WE DO THIS ALL THE TIME @loige 3

WE DO THIS ALL THE TIME WE DO THIS ALL THE TIME AND IT'S OK AND IT'S OK @loige 3

WE DO THIS ALL THE TIME WE DO THIS ALL THE TIME AND IT'S OK AND IT'S OK BUT SOMETIMES ... BUT SOMETIMES ... @loige 3

@loige ERR_FS_FILE_TOO_LARGE! ERR_FS_FILE_TOO_LARGE! File size is greater than possible Buffer 4

BUT WHY? BUT WHY? @loige 5

IF BYTES IF BYTES WERE WERE BLOCKS... BLOCKS... @loige 6

MARIO CAN LIFT MARIO CAN LIFT FEW BLOCKS FEW BLOCKS @loige 7

BUT NOT TOO MANY... BUT NOT TOO MANY... @loige ?! 8

WHAT CAN WE DO IF WE HAVE TO WHAT CAN WE DO IF WE HAVE TO MOVE MANY BLOCKS? MOVE MANY BLOCKS? @loige 9

WE CAN MOVE THEM ONE BY ONE! WE CAN MOVE THEM ONE BY ONE! @loige we stream them... 10

11

HELLO, I AM LUCIANO! HELLO, I AM LUCIANO! 11

HELLO, I AM LUCIANO! HELLO, I AM LUCIANO! 11

HELLO, I AM LUCIANO! HELLO, I AM LUCIANO! 11

HELLO, I AM LUCIANO! HELLO, I AM LUCIANO! 11

HELLO, I AM LUCIANO! HELLO, I AM LUCIANO! Cloud Architect 11

HELLO, I AM LUCIANO! HELLO, I AM LUCIANO! Cloud Architect Blog: Twitter: GitHub: loige.co @loige @lmammino 11

HELLO, I AM LUCIANO! HELLO, I AM LUCIANO! Cloud Architect Blog: Twitter: GitHub: loige.co @loige @lmammino 11

code: loige.link/streams-examples loige.link/streams-kyiv 12

01. BUFFERS VS 01. BUFFERS VS STREAMS STREAMS @loige 13

BUFFER BUFFER: DATA STRUCTURE TO STORE AND : DATA STRUCTURE TO STORE AND TRANSFER ARBITRARY BINARY DATA TRANSFER ARBITRARY BINARY DATA @loige *Note that this is loading all the content of the file in memory * 14

STREAM STREAM: ABSTRACT INTERFACE FOR : ABSTRACT INTERFACE FOR WORKING WITH STREAMING DATA WORKING WITH STREAMING DATA @loige *It does not load all the data straight away * 15

FILE COPY: FILE COPY: THE BUFFER WAY THE BUFFER WAY @loige // buffer-copy.js const { readFileSync, writeFileSync } = require('fs') const [,, src, dest] = process.argv const content = readFileSync(src) writeFileSync(dest, content) 1 2 3 4 5 6 7 8 9 10 16

FILE COPY: FILE COPY: THE STREAM WAY THE STREAM WAY // stream-copy.js const { createReadStream, createWriteStream } = require('fs') const [,, src, dest] = process.argv const srcStream = createReadStream(src) const destStream = createWriteStream(dest) srcStream.on('data', (data) => destStream.write(data)) 1 2 3 4 5 6 7 8 9 10 11 @loige * Careful: this implementation is not optimal * 17

FILE COPY: FILE COPY: THE STREAM WAY THE STREAM WAY // stream-copy.js const { createReadStream, createWriteStream } = require('fs') const [,, src, dest] = process.argv const srcStream = createReadStream(src) const destStream = createWriteStream(dest) srcStream.on('data', (data) => destStream.write(data)) 1 2 3 4 5 6 7 8 9 10 11 createReadStream, createWriteStream // stream-copy.js 1 2 const { 3 4 5 } = require('fs') 6 7 const [,, src, dest] = process.argv 8 const srcStream = createReadStream(src) 9 const destStream = createWriteStream(dest) 10 srcStream.on('data', (data) => destStream.write(data)) 11 @loige * Careful: this implementation is not optimal * 17

FILE COPY: FILE COPY: THE STREAM WAY THE STREAM WAY // stream-copy.js const { createReadStream, createWriteStream } = require('fs') const [,, src, dest] = process.argv const srcStream = createReadStream(src) const destStream = createWriteStream(dest) srcStream.on('data', (data) => destStream.write(data)) 1 2 3 4 5 6 7 8 9 10 11 createReadStream, createWriteStream // stream-copy.js 1 2 const { 3 4 5 } = require('fs') 6 7 const [,, src, dest] = process.argv 8 const srcStream = createReadStream(src) 9 const destStream = createWriteStream(dest) 10 srcStream.on('data', (data) => destStream.write(data)) 11 const srcStream = createReadStream(src) const destStream = createWriteStream(dest) // stream-copy.js 1 2 const { 3 createReadStream, 4 createWriteStream 5 } = require('fs') 6 7 const [,, src, dest] = process.argv 8 9 10 srcStream.on('data', (data) => destStream.write(data)) 11 @loige * Careful: this implementation is not optimal * 17

FILE COPY: FILE COPY: THE STREAM WAY THE STREAM WAY // stream-copy.js const { createReadStream, createWriteStream } = require('fs') const [,, src, dest] = process.argv const srcStream = createReadStream(src) const destStream = createWriteStream(dest) srcStream.on('data', (data) => destStream.write(data)) 1 2 3 4 5 6 7 8 9 10 11 createReadStream, createWriteStream // stream-copy.js 1 2 const { 3 4 5 } = require('fs') 6 7 const [,, src, dest] = process.argv 8 const srcStream = createReadStream(src) 9 const destStream = createWriteStream(dest) 10 srcStream.on('data', (data) => destStream.write(data)) 11 const srcStream = createReadStream(src) const destStream = createWriteStream(dest) // stream-copy.js 1 2 const { 3 createReadStream, 4 createWriteStream 5 } = require('fs') 6 7 const [,, src, dest] = process.argv 8 9 10 srcStream.on('data', (data) => destStream.write(data)) 11 srcStream.on('data', (data) => destStream.write(data)) // stream-copy.js 1 2 const { 3 createReadStream, 4 createWriteStream 5 } = require('fs') 6 7 const [,, src, dest] = process.argv 8 const srcStream = createReadStream(src) 9 const destStream = createWriteStream(dest) 10 11 @loige * Careful: this implementation is not optimal * 17

MEMORY COMPARISON (~600MB FILE) MEMORY COMPARISON (~600MB FILE) node ­­inspect­brk buffer­copy.js assets/poster.psd ~/Downloads/poster.psd @loige 18

MEMORY COMPARISON (~600MB FILE) MEMORY COMPARISON (~600MB FILE) node ­­inspect­brk stream­copy.js assets/poster.psd ~/Downloads/poster.psd @loige 19

LET'S TRY WITH A BIG FILE (~10GB) LET'S TRY WITH A BIG FILE (~10GB) @loige 20

LET'S TRY WITH A BIG FILE (~10GB) LET'S TRY WITH A BIG FILE (~10GB) node ­­inspect­brk stream­copy.js assets/the­matrix­hd.mkv ~/Downloads/the­matrix­hd.mkv @loige 21

STREAMS VS BUFFERS STREAMS VS BUFFERS Streams keep a low memory footprint even with large amounts of data Streams allows you to process data as soon as it arrives @loige 22

03. STREAM TYPES 03. STREAM TYPES & APIS & APIS @loige 23

ALL STREAMS ARE ALL STREAMS ARE EVENT EMITTERS EVENT EMITTERS A stream instance is an object that emits events when its internal state changes, for instance: s.on('readable', () => {}) // ready to be consumed s.on('data', (chunk) => {}) // new data is available s.on('error', (err) => {}) // some error happened s.on('end', () => {}) // no more data available The events available depend from the type of stream @loige 24

READABLE READABLE STREAMS STREAMS A readable stream represents a source from which data is consumed. Examples: fs readStream process.stdin HTTP response (client-side) HTTP request (server-side) AWS S3 GetObject (data field) It supports two modes for data consumption: flowing and paused (or non- flowing) mode. @loige 25

READABLE STREAMS READABLE STREAMS Data is read from source automatically and chunks are emitted as soon as they are available. @loige 26

@loige 1 2 3 Source data Readable stream in flowing mode data listener READABLE STREAMS READABLE STREAMS Data is read from source automatically and chunks are emitted as soon as they are available. 27

@loige 1 2 3 Source data Readable stream in flowing mode Read data listener READABLE STREAMS READABLE STREAMS Data is read from source automatically and chunks are emitted as soon as they are available. 28

@loige 1 2 3 Source data Readable stream in flowing mode data listener data READABLE STREAMS READABLE STREAMS Data is read from source automatically and chunks are emitted as soon as they are available. 29

@loige 2 3 Source data Readable stream in flowing mode data listener Read READABLE STREAMS READABLE STREAMS Data is read from source automatically and chunks are emitted as soon as they are available. 30

@loige 2 3 Source data Readable stream in flowing mode data listener data READABLE STREAMS READABLE STREAMS Data is read from source automatically and chunks are emitted as soon as they are available. 31

@loige 3 Source data Readable stream in flowing mode data listener Read READABLE STREAMS READABLE STREAMS Data is read from source automatically and chunks are emitted as soon as they are available. 32

@loige 3 Source data Readable stream in flowing mode data listener data READABLE STREAMS READABLE STREAMS Data is read from source automatically and chunks are emitted as soon as they are available. 33

@loige Source data Readable stream in flowing mode Read data listener (end) READABLE STREAMS READABLE STREAMS Data is read from source automatically and chunks are emitted as soon as they are available. 34

@loige Source data Readable stream in flowing mode data listener end (end) When no more data is available, end is emitted. READABLE STREAMS READABLE STREAMS Data is read from source automatically and chunks are emitted as soon as they are available. 35

// count-emojis-flowing.js const { createReadStream } = require('fs') const { EMOJI_MAP } = require('emoji') // from npm const emojis = Object.keys(EMOJI_MAP) const file = createReadStream(process.argv[2]) let counter = 0 file.on('data', chunk => { for (let char of chunk.toString('utf8')) { if (emojis.includes(char)) { counter++ } } }) file.on('end', () => console.log(`Found ${counter} emojis`)) file.on('error', err => console.error(`Error reading file: ${err}`)) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 @loige 36

// count-emojis-flowing.js const { createReadStream } = require('fs') const { EMOJI_MAP } = require('emoji') // from npm const emojis = Object.keys(EMOJI_MAP) const file = createReadStream(process.argv[2]) let counter = 0 file.on('data', chunk => { for (let char of chunk.toString('utf8')) { if (emojis.includes(char)) { counter++ } } }) file.on('end', () => console.log(`Found ${counter} emojis`)) file.on('error', err => console.error(`Error reading file: ${err}`)) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 const { EMOJI_MAP } = require('emoji') // from npm // count-emojis-flowing.js 1 2 const { createReadStream } = require('fs') 3 4 5 const emojis = Object.keys(EMOJI_MAP) 6 7 const file = createReadStream(process.argv[2]) 8 let counter = 0 9 10 file.on('data', chunk => { 11 for (let char of chunk.toString('utf8')) { 12 if (emojis.includes(char)) { 13 counter++ 14 } 15 } 16 }) 17 file.on('end', () => console.log(`Found ${counter} emojis`)) 18 file.on('error', err => console.error(`Error reading file: ${err}`)) 19 @loige 36

// count-emojis-flowing.js const { createReadStream } = require('fs') const { EMOJI_MAP } = require('emoji') // from npm const emojis = Object.keys(EMOJI_MAP) const file = createReadStream(process.argv[2]) let counter = 0 file.on('data', chunk => { for (let char of chunk.toString('utf8')) { if (emojis.includes(char)) { counter++ } } }) file.on('end', () => console.log(`Found ${counter} emojis`)) file.on('error', err => console.error(`Error reading file: ${err}`)) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 const { EMOJI_MAP } = require('emoji') // from npm // count-emojis-flowing.js 1 2 const { createReadStream } = require('fs') 3 4 5 const emojis = Object.keys(EMOJI_MAP) 6 7 const file = createReadStream(process.argv[2]) 8 let counter = 0 9 10 file.on('data', chunk => { 11 for (let char of chunk.toString('utf8')) { 12 if (emojis.includes(char)) { 13 counter++ 14 } 15 } 16 }) 17 file.on('end', () => console.log(`Found ${counter} emojis`)) 18 file.on('error', err => console.error(`Error reading file: ${err}`)) 19 const file = createReadStream(process.argv[2]) // count-emojis-flowing.js 1 2 const { createReadStream } = require('fs') 3 const { EMOJI_MAP } = require('emoji') // from npm 4 5 const emojis = Object.keys(EMOJI_MAP) 6 7 8 let counter = 0 9 10 file.on('data', chunk => { 11 for (let char of chunk.toString('utf8')) { 12 if (emojis.includes(char)) { 13 counter++ 14 } 15 } 16 }) 17 file.on('end', () => console.log(`Found ${counter} emojis`)) 18 file.on('error', err => console.error(`Error reading file: ${err}`)) 19 @loige 36

// count-emojis-flowing.js const { createReadStream } = require('fs') const { EMOJI_MAP } = require('emoji') // from npm const emojis = Object.keys(EMOJI_MAP) const file = createReadStream(process.argv[2]) let counter = 0 file.on('data', chunk => { for (let char of chunk.toString('utf8')) { if (emojis.includes(char)) { counter++ } } }) file.on('end', () => console.log(`Found ${counter} emojis`)) file.on('error', err => console.error(`Error reading file: ${err}`)) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 const { EMOJI_MAP } = require('emoji') // from npm // count-emojis-flowing.js 1 2 const { createReadStream } = require('fs') 3 4 5 const emojis = Object.keys(EMOJI_MAP) 6 7 const file = createReadStream(process.argv[2]) 8 let counter = 0 9 10 file.on('data', chunk => { 11 for (let char of chunk.toString('utf8')) { 12 if (emojis.includes(char)) { 13 counter++ 14 } 15 } 16 }) 17 file.on('end', () => console.log(`Found ${counter} emojis`)) 18 file.on('error', err => console.error(`Error reading file: ${err}`)) 19 const file = createReadStream(process.argv[2]) // count-emojis-flowing.js 1 2 const { createReadStream } = require('fs') 3 const { EMOJI_MAP } = require('emoji') // from npm 4 5 const emojis = Object.keys(EMOJI_MAP) 6 7 8 let counter = 0 9 10 file.on('data', chunk => { 11 for (let char of chunk.toString('utf8')) { 12 if (emojis.includes(char)) { 13 counter++ 14 } 15 } 16 }) 17 file.on('end', () => console.log(`Found ${counter} emojis`)) 18 file.on('error', err => console.error(`Error reading file: ${err}`)) 19 let counter = 0 // count-emojis-flowing.js 1 2 const { createReadStream } = require('fs') 3 const { EMOJI_MAP } = require('emoji') // from npm 4 5 const emojis = Object.keys(EMOJI_MAP) 6 7 const file = createReadStream(process.argv[2]) 8 9 10 file.on('data', chunk => { 11 for (let char of chunk.toString('utf8')) { 12 if (emojis.includes(char)) { 13 counter++ 14 } 15 } 16 }) 17 file.on('end', () => console.log(`Found ${counter} emojis`)) 18 file.on('error', err => console.error(`Error reading file: ${err}`)) 19 @loige 36

// count-emojis-flowing.js const { createReadStream } = require('fs') const { EMOJI_MAP } = require('emoji') // from npm const emojis = Object.keys(EMOJI_MAP) const file = createReadStream(process.argv[2]) let counter = 0 file.on('data', chunk => { for (let char of chunk.toString('utf8')) { if (emojis.includes(char)) { counter++ } } }) file.on('end', () => console.log(`Found ${counter} emojis`)) file.on('error', err => console.error(`Error reading file: ${err}`)) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 const { EMOJI_MAP } = require('emoji') // from npm // count-emojis-flowing.js 1 2 const { createReadStream } = require('fs') 3 4 5 const emojis = Object.keys(EMOJI_MAP) 6 7 const file = createReadStream(process.argv[2]) 8 let counter = 0 9 10 file.on('data', chunk => { 11 for (let char of chunk.toString('utf8')) { 12 if (emojis.includes(char)) { 13 counter++ 14 } 15 } 16 }) 17 file.on('end', () => console.log(`Found ${counter} emojis`)) 18 file.on('error', err => console.error(`Error reading file: ${err}`)) 19 const file = createReadStream(process.argv[2]) // count-emojis-flowing.js 1 2 const { createReadStream } = require('fs') 3 const { EMOJI_MAP } = require('emoji') // from npm 4 5 const emojis = Object.keys(EMOJI_MAP) 6 7 8 let counter = 0 9 10 file.on('data', chunk => { 11 for (let char of chunk.toString('utf8')) { 12 if (emojis.includes(char)) { 13 counter++ 14 } 15 } 16 }) 17 file.on('end', () => console.log(`Found ${counter} emojis`)) 18 file.on('error', err => console.error(`Error reading file: ${err}`)) 19 let counter = 0 // count-emojis-flowing.js 1 2 const { createReadStream } = require('fs') 3 const { EMOJI_MAP } = require('emoji') // from npm 4 5 const emojis = Object.keys(EMOJI_MAP) 6 7 const file = createReadStream(process.argv[2]) 8 9 10 file.on('data', chunk => { 11 for (let char of chunk.toString('utf8')) { 12 if (emojis.includes(char)) { 13 counter++ 14 } 15 } 16 }) 17 file.on('end', () => console.log(`Found ${counter} emojis`)) 18 file.on('error', err => console.error(`Error reading file: ${err}`)) 19 file.on('data', chunk => { }) // count-emojis-flowing.js 1 2 const { createReadStream } = require('fs') 3 const { EMOJI_MAP } = require('emoji') // from npm 4 5 const emojis = Object.keys(EMOJI_MAP) 6 7 const file = createReadStream(process.argv[2]) 8 let counter = 0 9 10 11 for (let char of chunk.toString('utf8')) { 12 if (emojis.includes(char)) { 13 counter++ 14 } 15 } 16 17 file.on('end', () => console.log(`Found ${counter} emojis`)) 18 file.on('error', err => console.error(`Error reading file: ${err}`)) 19 @loige 36

// count-emojis-flowing.js const { createReadStream } = require('fs') const { EMOJI_MAP } = require('emoji') // from npm const emojis = Object.keys(EMOJI_MAP) const file = createReadStream(process.argv[2]) let counter = 0 file.on('data', chunk => { for (let char of chunk.toString('utf8')) { if (emojis.includes(char)) { counter++ } } }) file.on('end', () => console.log(`Found ${counter} emojis`)) file.on('error', err => console.error(`Error reading file: ${err}`)) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 const { EMOJI_MAP } = require('emoji') // from npm // count-emojis-flowing.js 1 2 const { createReadStream } = require('fs') 3 4 5 const emojis = Object.keys(EMOJI_MAP) 6 7 const file = createReadStream(process.argv[2]) 8 let counter = 0 9 10 file.on('data', chunk => { 11 for (let char of chunk.toString('utf8')) { 12 if (emojis.includes(char)) { 13 counter++ 14 } 15 } 16 }) 17 file.on('end', () => console.log(`Found ${counter} emojis`)) 18 file.on('error', err => console.error(`Error reading file: ${err}`)) 19 const file = createReadStream(process.argv[2]) // count-emojis-flowing.js 1 2 const { createReadStream } = require('fs') 3 const { EMOJI_MAP } = require('emoji') // from npm 4 5 const emojis = Object.keys(EMOJI_MAP) 6 7 8 let counter = 0 9 10 file.on('data', chunk => { 11 for (let char of chunk.toString('utf8')) { 12 if (emojis.includes(char)) { 13 counter++ 14 } 15 } 16 }) 17 file.on('end', () => console.log(`Found ${counter} emojis`)) 18 file.on('error', err => console.error(`Error reading file: ${err}`)) 19 let counter = 0 // count-emojis-flowing.js 1 2 const { createReadStream } = require('fs') 3 const { EMOJI_MAP } = require('emoji') // from npm 4 5 const emojis = Object.keys(EMOJI_MAP) 6 7 const file = createReadStream(process.argv[2]) 8 9 10 file.on('data', chunk => { 11 for (let char of chunk.toString('utf8')) { 12 if (emojis.includes(char)) { 13 counter++ 14 } 15 } 16 }) 17 file.on('end', () => console.log(`Found ${counter} emojis`)) 18 file.on('error', err => console.error(`Error reading file: ${err}`)) 19 file.on('data', chunk => { }) // count-emojis-flowing.js 1 2 const { createReadStream } = require('fs') 3 const { EMOJI_MAP } = require('emoji') // from npm 4 5 const emojis = Object.keys(EMOJI_MAP) 6 7 const file = createReadStream(process.argv[2]) 8 let counter = 0 9 10 11 for (let char of chunk.toString('utf8')) { 12 if (emojis.includes(char)) { 13 counter++ 14 } 15 } 16 17 file.on('end', () => console.log(`Found ${counter} emojis`)) 18 file.on('error', err => console.error(`Error reading file: ${err}`)) 19 for (let char of chunk.toString('utf8')) { } // count-emojis-flowing.js 1 2 const { createReadStream } = require('fs') 3 const { EMOJI_MAP } = require('emoji') // from npm 4 5 const emojis = Object.keys(EMOJI_MAP) 6 7 const file = createReadStream(process.argv[2]) 8 let counter = 0 9 10 file.on('data', chunk => { 11 12 if (emojis.includes(char)) { 13 counter++ 14 } 15 16 }) 17 file.on('end', () => console.log(`Found ${counter} emojis`)) 18 file.on('error', err => console.error(`Error reading file: ${err}`)) 19 @loige 36

// count-emojis-flowing.js const { createReadStream } = require('fs') const { EMOJI_MAP } = require('emoji') // from npm const emojis = Object.keys(EMOJI_MAP) const file = createReadStream(process.argv[2]) let counter = 0 file.on('data', chunk => { for (let char of chunk.toString('utf8')) { if (emojis.includes(char)) { counter++ } } }) file.on('end', () => console.log(`Found ${counter} emojis`)) file.on('error', err => console.error(`Error reading file: ${err}`)) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 const { EMOJI_MAP } = require('emoji') // from npm // count-emojis-flowing.js 1 2 const { createReadStream } = require('fs') 3 4 5 const emojis = Object.keys(EMOJI_MAP) 6 7 const file = createReadStream(process.argv[2]) 8 let counter = 0 9 10 file.on('data', chunk => { 11 for (let char of chunk.toString('utf8')) { 12 if (emojis.includes(char)) { 13 counter++ 14 } 15 } 16 }) 17 file.on('end', () => console.log(`Found ${counter} emojis`)) 18 file.on('error', err => console.error(`Error reading file: ${err}`)) 19 const file = createReadStream(process.argv[2]) // count-emojis-flowing.js 1 2 const { createReadStream } = require('fs') 3 const { EMOJI_MAP } = require('emoji') // from npm 4 5 const emojis = Object.keys(EMOJI_MAP) 6 7 8 let counter = 0 9 10 file.on('data', chunk => { 11 for (let char of chunk.toString('utf8')) { 12 if (emojis.includes(char)) { 13 counter++ 14 } 15 } 16 }) 17 file.on('end', () => console.log(`Found ${counter} emojis`)) 18 file.on('error', err => console.error(`Error reading file: ${err}`)) 19 let counter = 0 // count-emojis-flowing.js 1 2 const { createReadStream } = require('fs') 3 const { EMOJI_MAP } = require('emoji') // from npm 4 5 const emojis = Object.keys(EMOJI_MAP) 6 7 const file = createReadStream(process.argv[2]) 8 9 10 file.on('data', chunk => { 11 for (let char of chunk.toString('utf8')) { 12 if (emojis.includes(char)) { 13 counter++ 14 } 15 } 16 }) 17 file.on('end', () => console.log(`Found ${counter} emojis`)) 18 file.on('error', err => console.error(`Error reading file: ${err}`)) 19 file.on('data', chunk => { }) // count-emojis-flowing.js 1 2 const { createReadStream } = require('fs') 3 const { EMOJI_MAP } = require('emoji') // from npm 4 5 const emojis = Object.keys(EMOJI_MAP) 6 7 const file = createReadStream(process.argv[2]) 8 let counter = 0 9 10 11 for (let char of chunk.toString('utf8')) { 12 if (emojis.includes(char)) { 13 counter++ 14 } 15 } 16 17 file.on('end', () => console.log(`Found ${counter} emojis`)) 18 file.on('error', err => console.error(`Error reading file: ${err}`)) 19 for (let char of chunk.toString('utf8')) { } // count-emojis-flowing.js 1 2 const { createReadStream } = require('fs') 3 const { EMOJI_MAP } = require('emoji') // from npm 4 5 const emojis = Object.keys(EMOJI_MAP) 6 7 const file = createReadStream(process.argv[2]) 8 let counter = 0 9 10 file.on('data', chunk => { 11 12 if (emojis.includes(char)) { 13 counter++ 14 } 15 16 }) 17 file.on('end', () => console.log(`Found ${counter} emojis`)) 18 file.on('error', err => console.error(`Error reading file: ${err}`)) 19 if (emojis.includes(char)) { counter++ } // count-emojis-flowing.js 1 2 const { createReadStream } = require('fs') 3 const { EMOJI_MAP } = require('emoji') // from npm 4 5 const emojis = Object.keys(EMOJI_MAP) 6 7 const file = createReadStream(process.argv[2]) 8 let counter = 0 9 10 file.on('data', chunk => { 11 for (let char of chunk.toString('utf8')) { 12 13 14 15 } 16 }) 17 file.on('end', () => console.log(`Found ${counter} emojis`)) 18 file.on('error', err => console.error(`Error reading file: ${err}`)) 19 @loige 36

loige.link/up-emojiart @loige 37

READABLE STREAMS ARE READABLE STREAMS ARE ALSO ALSO ASYNC ITERATORS ASYNC ITERATORS ( (NODE.JS 10+) NODE.JS 10+) @loige 38

// count-emojis-async-iterator.js const { createReadStream } = require('fs') const { EMOJI_MAP } = require('emoji') // from npm async function main () { const emojis = Object.keys(EMOJI_MAP) const file = createReadStream(process.argv[2]) let counter = 0 for await (let chunk of file) { for (let char of chunk.toString('utf8')) { if (emojis.includes(char)) { counter++ } } } console.log(`Found ${counter} emojis`) } main() 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 @loige 39

// count-emojis-async-iterator.js const { createReadStream } = require('fs') const { EMOJI_MAP } = require('emoji') // from npm async function main () { const emojis = Object.keys(EMOJI_MAP) const file = createReadStream(process.argv[2]) let counter = 0 for await (let chunk of file) { for (let char of chunk.toString('utf8')) { if (emojis.includes(char)) { counter++ } } } console.log(`Found ${counter} emojis`) } main() 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 for await (let chunk of file) { } // count-emojis-async-iterator.js 1 const { createReadStream } = require('fs') 2 const { EMOJI_MAP } = require('emoji') // from npm 3 4 async function main () { 5 const emojis = Object.keys(EMOJI_MAP) 6 const file = createReadStream(process.argv[2]) 7 let counter = 0 8 9 10 for (let char of chunk.toString('utf8')) { 11 if (emojis.includes(char)) { 12 counter++ 13 } 14 } 15 16 17 console.log(`Found ${counter} emojis`) 18 } 19 20 main() 21 @loige 39

// count-emojis-async-iterator.js const { createReadStream } = require('fs') const { EMOJI_MAP } = require('emoji') // from npm async function main () { const emojis = Object.keys(EMOJI_MAP) const file = createReadStream(process.argv[2]) let counter = 0 for await (let chunk of file) { for (let char of chunk.toString('utf8')) { if (emojis.includes(char)) { counter++ } } } console.log(`Found ${counter} emojis`) } main() 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 for await (let chunk of file) { } // count-emojis-async-iterator.js 1 const { createReadStream } = require('fs') 2 const { EMOJI_MAP } = require('emoji') // from npm 3 4 async function main () { 5 const emojis = Object.keys(EMOJI_MAP) 6 const file = createReadStream(process.argv[2]) 7 let counter = 0 8 9 10 for (let char of chunk.toString('utf8')) { 11 if (emojis.includes(char)) { 12 counter++ 13 } 14 } 15 16 17 console.log(`Found ${counter} emojis`) 18 } 19 20 main() 21 async function main () { } // count-emojis-async-iterator.js 1 const { createReadStream } = require('fs') 2 const { EMOJI_MAP } = require('emoji') // from npm 3 4 5 const emojis = Object.keys(EMOJI_MAP) 6 const file = createReadStream(process.argv[2]) 7 let counter = 0 8 9 for await (let chunk of file) { 10 for (let char of chunk.toString('utf8')) { 11 if (emojis.includes(char)) { 12 counter++ 13 } 14 } 15 } 16 17 console.log(`Found ${counter} emojis`) 18 19 20 main() 21 @loige 39

WRITABLE WRITABLE STREAMS STREAMS A writable stream is an abstraction that allows to write data over a destination Examples: fs writeStream process.stdout, process.stderr HTTP request (client-side) HTTP response (server-side) AWS S3 PutObject (body parameter) @loige 40

// writable-http-request.js const http = require('http') const req = http.request( { hostname: 'enx6b07hdu6cs.x.pipedream.net', method: 'POST' }, resp => { console.log(`Server responded with "${resp.statusCode}"`) } ) req.on('finish', () => console.log('request sent')) req.on('close', () => console.log('Connection closed')) req.on('error', err => console.error(`Request failed: ${err}`)) req.write('writing some content...\n') req.end('last write & close the stream') 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 @loige 41

// writable-http-request.js const http = require('http') const req = http.request( { hostname: 'enx6b07hdu6cs.x.pipedream.net', method: 'POST' }, resp => { console.log(`Server responded with "${resp.statusCode}"`) } ) req.on('finish', () => console.log('request sent')) req.on('close', () => console.log('Connection closed')) req.on('error', err => console.error(`Request failed: ${err}`)) req.write('writing some content...\n') req.end('last write & close the stream') 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 const req = http.request( ) // writable-http-request.js 1 const http = require('http') 2 3 4 { 5 hostname: 'enx6b07hdu6cs.x.pipedream.net', 6 method: 'POST' 7 }, 8 resp => { 9 console.log(`Server responded with "${resp.statusCode}"`) 10 } 11 12 13 req.on('finish', () => console.log('request sent')) 14 req.on('close', () => console.log('Connection closed')) 15 req.on('error', err => console.error(`Request failed: ${err}`)) 16 17 req.write('writing some content...\n') 18 req.end('last write & close the stream') 19 @loige 41

// writable-http-request.js const http = require('http') const req = http.request( { hostname: 'enx6b07hdu6cs.x.pipedream.net', method: 'POST' }, resp => { console.log(`Server responded with "${resp.statusCode}"`) } ) req.on('finish', () => console.log('request sent')) req.on('close', () => console.log('Connection closed')) req.on('error', err => console.error(`Request failed: ${err}`)) req.write('writing some content...\n') req.end('last write & close the stream') 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 const req = http.request( ) // writable-http-request.js 1 const http = require('http') 2 3 4 { 5 hostname: 'enx6b07hdu6cs.x.pipedream.net', 6 method: 'POST' 7 }, 8 resp => { 9 console.log(`Server responded with "${resp.statusCode}"`) 10 } 11 12 13 req.on('finish', () => console.log('request sent')) 14 req.on('close', () => console.log('Connection closed')) 15 req.on('error', err => console.error(`Request failed: ${err}`)) 16 17 req.write('writing some content...\n') 18 req.end('last write & close the stream') 19 req.on('finish', () => console.log('request sent')) req.on('close', () => console.log('Connection closed')) req.on('error', err => console.error(`Request failed: ${err}`)) // writable-http-request.js 1 const http = require('http') 2 3 const req = http.request( 4 { 5 hostname: 'enx6b07hdu6cs.x.pipedream.net', 6 method: 'POST' 7 }, 8 resp => { 9 console.log(`Server responded with "${resp.statusCode}"`) 10 } 11 ) 12 13 14 15 16 17 req.write('writing some content...\n') 18 req.end('last write & close the stream') 19 @loige 41

// writable-http-request.js const http = require('http') const req = http.request( { hostname: 'enx6b07hdu6cs.x.pipedream.net', method: 'POST' }, resp => { console.log(`Server responded with "${resp.statusCode}"`) } ) req.on('finish', () => console.log('request sent')) req.on('close', () => console.log('Connection closed')) req.on('error', err => console.error(`Request failed: ${err}`)) req.write('writing some content...\n') req.end('last write & close the stream') 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 const req = http.request( ) // writable-http-request.js 1 const http = require('http') 2 3 4 { 5 hostname: 'enx6b07hdu6cs.x.pipedream.net', 6 method: 'POST' 7 }, 8 resp => { 9 console.log(`Server responded with "${resp.statusCode}"`) 10 } 11 12 13 req.on('finish', () => console.log('request sent')) 14 req.on('close', () => console.log('Connection closed')) 15 req.on('error', err => console.error(`Request failed: ${err}`)) 16 17 req.write('writing some content...\n') 18 req.end('last write & close the stream') 19 req.on('finish', () => console.log('request sent')) req.on('close', () => console.log('Connection closed')) req.on('error', err => console.error(`Request failed: ${err}`)) // writable-http-request.js 1 const http = require('http') 2 3 const req = http.request( 4 { 5 hostname: 'enx6b07hdu6cs.x.pipedream.net', 6 method: 'POST' 7 }, 8 resp => { 9 console.log(`Server responded with "${resp.statusCode}"`) 10 } 11 ) 12 13 14 15 16 17 req.write('writing some content...\n') 18 req.end('last write & close the stream') 19 req.write('writing some content...\n') req.end('last write & close the stream') // writable-http-request.js 1 const http = require('http') 2 3 const req = http.request( 4 { 5 hostname: 'enx6b07hdu6cs.x.pipedream.net', 6 method: 'POST' 7 }, 8 resp => { 9 console.log(`Server responded with "${resp.statusCode}"`) 10 } 11 ) 12 13 req.on('finish', () => console.log('request sent')) 14 req.on('close', () => console.log('Connection closed')) 15 req.on('error', err => console.error(`Request failed: ${err}`)) 16 17 18 19 @loige 41

@loige 42

loige.link/writable-http-req @loige 43

BACKPRESSURE BACKPRESSURE When writing large amounts of data you should make sure you handle the stop write signal and the drain event loige.link/backpressure @loige 44

// stream-copy-safe.js const { createReadStream, createWriteStream } = require('fs') const [, , src, dest] = process.argv const srcStream = createReadStream(src) const destStream = createWriteStream(dest) srcStream.on('data', data => { const canContinue = destStream.write(data) if (!canContinue) { // we are overflowing the destination, we should pause srcStream.pause() // we will resume when the destination stream is drained destStream.once('drain', () => srcStream.resume()) } }) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 @loige 45

// stream-copy-safe.js const { createReadStream, createWriteStream } = require('fs') const [, , src, dest] = process.argv const srcStream = createReadStream(src) const destStream = createWriteStream(dest) srcStream.on('data', data => { const canContinue = destStream.write(data) if (!canContinue) { // we are overflowing the destination, we should pause srcStream.pause() // we will resume when the destination stream is drained destStream.once('drain', () => srcStream.resume()) } }) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 const canContinue = destStream.write(data) // stream-copy-safe.js 1 2 const { createReadStream, createWriteStream } = require('fs') 3 4 const [, , src, dest] = process.argv 5 const srcStream = createReadStream(src) 6 const destStream = createWriteStream(dest) 7 8 srcStream.on('data', data => { 9 10 if (!canContinue) { 11 // we are overflowing the destination, we should pause 12 srcStream.pause() 13 // we will resume when the destination stream is drained 14 destStream.once('drain', () => srcStream.resume()) 15 } 16 }) 17 @loige 45

// stream-copy-safe.js const { createReadStream, createWriteStream } = require('fs') const [, , src, dest] = process.argv const srcStream = createReadStream(src) const destStream = createWriteStream(dest) srcStream.on('data', data => { const canContinue = destStream.write(data) if (!canContinue) { // we are overflowing the destination, we should pause srcStream.pause() // we will resume when the destination stream is drained destStream.once('drain', () => srcStream.resume()) } }) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 const canContinue = destStream.write(data) // stream-copy-safe.js 1 2 const { createReadStream, createWriteStream } = require('fs') 3 4 const [, , src, dest] = process.argv 5 const srcStream = createReadStream(src) 6 const destStream = createWriteStream(dest) 7 8 srcStream.on('data', data => { 9 10 if (!canContinue) { 11 // we are overflowing the destination, we should pause 12 srcStream.pause() 13 // we will resume when the destination stream is drained 14 destStream.once('drain', () => srcStream.resume()) 15 } 16 }) 17 if (!canContinue) { } // stream-copy-safe.js 1 2 const { createReadStream, createWriteStream } = require('fs') 3 4 const [, , src, dest] = process.argv 5 const srcStream = createReadStream(src) 6 const destStream = createWriteStream(dest) 7 8 srcStream.on('data', data => { 9 const canContinue = destStream.write(data) 10 11 // we are overflowing the destination, we should pause 12 srcStream.pause() 13 // we will resume when the destination stream is drained 14 destStream.once('drain', () => srcStream.resume()) 15 16 }) 17 @loige 45

// stream-copy-safe.js const { createReadStream, createWriteStream } = require('fs') const [, , src, dest] = process.argv const srcStream = createReadStream(src) const destStream = createWriteStream(dest) srcStream.on('data', data => { const canContinue = destStream.write(data) if (!canContinue) { // we are overflowing the destination, we should pause srcStream.pause() // we will resume when the destination stream is drained destStream.once('drain', () => srcStream.resume()) } }) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 const canContinue = destStream.write(data) // stream-copy-safe.js 1 2 const { createReadStream, createWriteStream } = require('fs') 3 4 const [, , src, dest] = process.argv 5 const srcStream = createReadStream(src) 6 const destStream = createWriteStream(dest) 7 8 srcStream.on('data', data => { 9 10 if (!canContinue) { 11 // we are overflowing the destination, we should pause 12 srcStream.pause() 13 // we will resume when the destination stream is drained 14 destStream.once('drain', () => srcStream.resume()) 15 } 16 }) 17 if (!canContinue) { } // stream-copy-safe.js 1 2 const { createReadStream, createWriteStream } = require('fs') 3 4 const [, , src, dest] = process.argv 5 const srcStream = createReadStream(src) 6 const destStream = createWriteStream(dest) 7 8 srcStream.on('data', data => { 9 const canContinue = destStream.write(data) 10 11 // we are overflowing the destination, we should pause 12 srcStream.pause() 13 // we will resume when the destination stream is drained 14 destStream.once('drain', () => srcStream.resume()) 15 16 }) 17 // we are overflowing the destination, we should pause srcStream.pause() // stream-copy-safe.js 1 2 const { createReadStream, createWriteStream } = require('fs') 3 4 const [, , src, dest] = process.argv 5 const srcStream = createReadStream(src) 6 const destStream = createWriteStream(dest) 7 8 srcStream.on('data', data => { 9 const canContinue = destStream.write(data) 10 if (!canContinue) { 11 12 13 // we will resume when the destination stream is drained 14 destStream.once('drain', () => srcStream.resume()) 15 } 16 }) 17 @loige 45

// stream-copy-safe.js const { createReadStream, createWriteStream } = require('fs') const [, , src, dest] = process.argv const srcStream = createReadStream(src) const destStream = createWriteStream(dest) srcStream.on('data', data => { const canContinue = destStream.write(data) if (!canContinue) { // we are overflowing the destination, we should pause srcStream.pause() // we will resume when the destination stream is drained destStream.once('drain', () => srcStream.resume()) } }) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 const canContinue = destStream.write(data) // stream-copy-safe.js 1 2 const { createReadStream, createWriteStream } = require('fs') 3 4 const [, , src, dest] = process.argv 5 const srcStream = createReadStream(src) 6 const destStream = createWriteStream(dest) 7 8 srcStream.on('data', data => { 9 10 if (!canContinue) { 11 // we are overflowing the destination, we should pause 12 srcStream.pause() 13 // we will resume when the destination stream is drained 14 destStream.once('drain', () => srcStream.resume()) 15 } 16 }) 17 if (!canContinue) { } // stream-copy-safe.js 1 2 const { createReadStream, createWriteStream } = require('fs') 3 4 const [, , src, dest] = process.argv 5 const srcStream = createReadStream(src) 6 const destStream = createWriteStream(dest) 7 8 srcStream.on('data', data => { 9 const canContinue = destStream.write(data) 10 11 // we are overflowing the destination, we should pause 12 srcStream.pause() 13 // we will resume when the destination stream is drained 14 destStream.once('drain', () => srcStream.resume()) 15 16 }) 17 // we are overflowing the destination, we should pause srcStream.pause() // stream-copy-safe.js 1 2 const { createReadStream, createWriteStream } = require('fs') 3 4 const [, , src, dest] = process.argv 5 const srcStream = createReadStream(src) 6 const destStream = createWriteStream(dest) 7 8 srcStream.on('data', data => { 9 const canContinue = destStream.write(data) 10 if (!canContinue) { 11 12 13 // we will resume when the destination stream is drained 14 destStream.once('drain', () => srcStream.resume()) 15 } 16 }) 17 // we will resume when the destination stream is drained destStream.once('drain', () => srcStream.resume()) // stream-copy-safe.js 1 2 const { createReadStream, createWriteStream } = require('fs') 3 4 const [, , src, dest] = process.argv 5 const srcStream = createReadStream(src) 6 const destStream = createWriteStream(dest) 7 8 srcStream.on('data', data => { 9 const canContinue = destStream.write(data) 10 if (!canContinue) { 11 // we are overflowing the destination, we should pause 12 srcStream.pause() 13 14 15 } 16 }) 17 @loige 45

// stream-copy-safe.js const { createReadStream, createWriteStream } = require('fs') const [, , src, dest] = process.argv const srcStream = createReadStream(src) const destStream = createWriteStream(dest) srcStream.on('data', data => { const canContinue = destStream.write(data) if (!canContinue) { // we are overflowing the destination, we should pause srcStream.pause() // we will resume when the destination stream is drained destStream.once('drain', () => srcStream.resume()) } }) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 const canContinue = destStream.write(data) // stream-copy-safe.js 1 2 const { createReadStream, createWriteStream } = require('fs') 3 4 const [, , src, dest] = process.argv 5 const srcStream = createReadStream(src) 6 const destStream = createWriteStream(dest) 7 8 srcStream.on('data', data => { 9 10 if (!canContinue) { 11 // we are overflowing the destination, we should pause 12 srcStream.pause() 13 // we will resume when the destination stream is drained 14 destStream.once('drain', () => srcStream.resume()) 15 } 16 }) 17 if (!canContinue) { } // stream-copy-safe.js 1 2 const { createReadStream, createWriteStream } = require('fs') 3 4 const [, , src, dest] = process.argv 5 const srcStream = createReadStream(src) 6 const destStream = createWriteStream(dest) 7 8 srcStream.on('data', data => { 9 const canContinue = destStream.write(data) 10 11 // we are overflowing the destination, we should pause 12 srcStream.pause() 13 // we will resume when the destination stream is drained 14 destStream.once('drain', () => srcStream.resume()) 15 16 }) 17 // we are overflowing the destination, we should pause srcStream.pause() // stream-copy-safe.js 1 2 const { createReadStream, createWriteStream } = require('fs') 3 4 const [, , src, dest] = process.argv 5 const srcStream = createReadStream(src) 6 const destStream = createWriteStream(dest) 7 8 srcStream.on('data', data => { 9 const canContinue = destStream.write(data) 10 if (!canContinue) { 11 12 13 // we will resume when the destination stream is drained 14 destStream.once('drain', () => srcStream.resume()) 15 } 16 }) 17 // we will resume when the destination stream is drained destStream.once('drain', () => srcStream.resume()) // stream-copy-safe.js 1 2 const { createReadStream, createWriteStream } = require('fs') 3 4 const [, , src, dest] = process.argv 5 const srcStream = createReadStream(src) 6 const destStream = createWriteStream(dest) 7 8 srcStream.on('data', data => { 9 const canContinue = destStream.write(data) 10 if (!canContinue) { 11 // we are overflowing the destination, we should pause 12 srcStream.pause() 13 14 15 } 16 }) 17 const canContinue = destStream.write(data) if (!canContinue) { // we are overflowing the destination, we should pause srcStream.pause() // we will resume when the destination stream is drained destStream.once('drain', () => srcStream.resume()) } // stream-copy-safe.js 1 2 const { createReadStream, createWriteStream } = require('fs') 3 4 const [, , src, dest] = process.argv 5 const srcStream = createReadStream(src) 6 const destStream = createWriteStream(dest) 7 8 srcStream.on('data', data => { 9 10 11 12 13 14 15 16 }) 17 @loige 45

OTHER TYPES OF STREAM OTHER TYPES OF STREAM Duplex Stream streams that are both Readable and Writable. (net.Socket) Transform Stream Duplex streams that can modify or transform the data as it is written and read. (zlib.createGzip(), crypto.createCipheriv()) @loige 46

ANATOMY OF A TRANSFORM STREAM ANATOMY OF A TRANSFORM STREAM transform stream @loige 47

ANATOMY OF A TRANSFORM STREAM ANATOMY OF A TRANSFORM STREAM 1. write data transform stream (readable stream) @loige 47

ANATOMY OF A TRANSFORM STREAM ANATOMY OF A TRANSFORM STREAM 1. write data transform stream 2. transform the data (readable stream) @loige 47

ANATOMY OF A TRANSFORM STREAM ANATOMY OF A TRANSFORM STREAM 1. write data transform stream 3. read transformed data 2. transform the data (readable stream) (writable stream) @loige 47

GZIP EXAMPLE GZIP EXAMPLE 1. write data transform stream 3. read transformed data 2. transform the data (readable stream) (writable stream) @loige 48

GZIP EXAMPLE GZIP EXAMPLE 1. write data transform stream 3. read transformed data 2. transform the data (readable stream) (writable stream) @loige Uncompressed data 48

GZIP EXAMPLE GZIP EXAMPLE 1. write data transform stream 3. read transformed data 2. transform the data (readable stream) (writable stream) @loige Uncompressed data compress zlib.createGzip() 48

GZIP EXAMPLE GZIP EXAMPLE 1. write data transform stream 3. read transformed data 2. transform the data (readable stream) (writable stream) @loige Uncompressed data Compressed data compress zlib.createGzip() 48

HOW CAN WE USE TRANSFORM STREAMS? HOW CAN WE USE TRANSFORM STREAMS? Readable Transform Writable 49 @loige

HOW CAN WE USE TRANSFORM STREAMS? HOW CAN WE USE TRANSFORM STREAMS? Readable Transform Writable ⚡ data 49 @loige

HOW CAN WE USE TRANSFORM STREAMS? HOW CAN WE USE TRANSFORM STREAMS? Readable Transform Writable ⚡ data write() 49 @loige

HOW CAN WE USE TRANSFORM STREAMS? HOW CAN WE USE TRANSFORM STREAMS? Readable Transform Writable ⚡ data write() ⚡ data 49 @loige

HOW CAN WE USE TRANSFORM STREAMS? HOW CAN WE USE TRANSFORM STREAMS? Readable Transform Writable ⚡ data write() ⚡ data write() 49 @loige

HOW CAN WE USE TRANSFORM STREAMS? HOW CAN WE USE TRANSFORM STREAMS? Readable Transform Writable ⚡ data write() ⚡ data write() 49 @loige (Backpressure)

HOW CAN WE USE TRANSFORM STREAMS? HOW CAN WE USE TRANSFORM STREAMS? Readable Transform Writable ⚡ data write() ⚡ data write() pause() 49 @loige (Backpressure)

HOW CAN WE USE TRANSFORM STREAMS? HOW CAN WE USE TRANSFORM STREAMS? Readable Transform Writable ⚡ data write() ⚡ data write() pause() ⚡ drain 49 @loige (Backpressure)

HOW CAN WE USE TRANSFORM STREAMS? HOW CAN WE USE TRANSFORM STREAMS? Readable Transform Writable ⚡ data write() ⚡ data write() pause() ⚡ drain resume() 49 @loige (Backpressure)

HOW CAN WE USE TRANSFORM STREAMS? HOW CAN WE USE TRANSFORM STREAMS? Readable Transform Writable ⚡ data write() ⚡ data write() pause() ⚡ drain resume() 49 @loige (Backpressure) (Backpressure)

HOW CAN WE USE TRANSFORM STREAMS? HOW CAN WE USE TRANSFORM STREAMS? Readable Transform Writable ⚡ data write() ⚡ data write() pause() ⚡ drain resume() pause() 49 @loige (Backpressure) (Backpressure)

HOW CAN WE USE TRANSFORM STREAMS? HOW CAN WE USE TRANSFORM STREAMS? Readable Transform Writable ⚡ data write() ⚡ data write() pause() ⚡ drain resume() pause() ⚡ drain 49 @loige (Backpressure) (Backpressure)

HOW CAN WE USE TRANSFORM STREAMS? HOW CAN WE USE TRANSFORM STREAMS? Readable Transform Writable ⚡ data write() ⚡ data write() pause() ⚡ drain resume() pause() ⚡ drain resume() 49 @loige (Backpressure) (Backpressure)

HOW CAN WE USE TRANSFORM STREAMS? HOW CAN WE USE TRANSFORM STREAMS? Readable Transform Writable ⚡ data write() ⚡ data write() pause() ⚡ drain resume() pause() ⚡ drain resume() 49 @loige (Backpressure) (Backpressure) You also have to handle end & error events!

gzipStream.on('data', data => { const canContinue = destStream.write(data) if (!canContinue) { gzipStream.pause() destStream.once('drain', () => { gzipStream.resume() }) } }) gzipStream.on('end', () => { destStream.end() }) // ⚠ TODO: handle errors! // stream-copy-gzip.js const { createReadStream, createWriteStream } = require('fs') const { createGzip } = require('zlib') const [, , src, dest] = process.argv const srcStream = createReadStream(src) const gzipStream = createGzip() const destStream = createWriteStream(dest) srcStream.on('data', data => { const canContinue = gzipStream.write(data) if (!canContinue) { srcStream.pause() gzipStream.once('drain', () => { srcStream.resume() }) } }) srcStream.on('end', () => { // check if there's buffered data left const remainingData = gzipStream.read() if (remainingData !== null) { destStream.write() } gzipStream.end() }) @loige 50

gzipStream.on('data', data => { const canContinue = destStream.write(data) if (!canContinue) { gzipStream.pause() destStream.once('drain', () => { gzipStream.resume() }) } }) gzipStream.on('end', () => { destStream.end() }) // ⚠ TODO: handle errors! // stream-copy-gzip.js const { createReadStream, createWriteStream } = require('fs') const { createGzip } = require('zlib') const [, , src, dest] = process.argv const srcStream = createReadStream(src) const gzipStream = createGzip() const destStream = createWriteStream(dest) srcStream.on('data', data => { const canContinue = gzipStream.write(data) if (!canContinue) { srcStream.pause() gzipStream.once('drain', () => { srcStream.resume() }) } }) srcStream.on('end', () => { // check if there's buffered data left const remainingData = gzipStream.read() if (remainingData !== null) { destStream.write() } gzipStream.end() }) @loige 50

03. PIPE() 03. PIPE() @loige 51

readable .pipe(tranform1) .pipe(transform2) .pipe(transform3) .pipe(writable) readable.pipe(writableDest) @loige Connects a readable stream to a writable stream A transform stream can be used as a destination as well It returns the destination stream allowing for a chain of pipes 52

// stream-copy-gzip-pipe.js const { createReadStream, createWriteStream } = require('fs') const { createGzip } = require('zlib') const [, , src, dest] = process.argv const srcStream = createReadStream(src) const gzipStream = createGzip() const destStream = createWriteStream(dest) srcStream .pipe(gzipStream) .pipe(destStream) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 @loige 53

// stream-copy-gzip-pipe.js const { createReadStream, createWriteStream } = require('fs') const { createGzip } = require('zlib') const [, , src, dest] = process.argv const srcStream = createReadStream(src) const gzipStream = createGzip() const destStream = createWriteStream(dest) srcStream .pipe(gzipStream) .pipe(destStream) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 srcStream .pipe(gzipStream) .pipe(destStream) // stream-copy-gzip-pipe.js 1 2 const { 3 createReadStream, 4 createWriteStream 5 } = require('fs') 6 const { createGzip } = require('zlib') 7 8 const [, , src, dest] = process.argv 9 const srcStream = createReadStream(src) 10 const gzipStream = createGzip() 11 const destStream = createWriteStream(dest) 12 13 14 15 16 @loige 53

readable .pipe(decompress) .pipe(decrypt) .pipe(convert) .pipe(encrypt) .pipe(compress) .pipe(writeToDisk) Setup complex pipelines with pipe @loige This is the most common way to use streams 54

readable .on('error', handleErr) .pipe(decompress) .on('error', handleErr) .pipe(decrypt) .on('error', handleErr) .pipe(convert) .on('error', handleErr) .pipe(encrypt) .on('error', handleErr) .pipe(compress) .on('error', handleErr) .pipe(writeToDisk) .on('error', handleErr) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Handling errors (correctly) @loige 55

readable .on('error', handleErr) .pipe(decompress) .on('error', handleErr) .pipe(decrypt) .on('error', handleErr) .pipe(convert) .on('error', handleErr) .pipe(encrypt) .on('error', handleErr) .pipe(compress) .on('error', handleErr) .pipe(writeToDisk) .on('error', handleErr) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 readable .pipe(decompress) .pipe(decrypt) .pipe(convert) .pipe(encrypt) .pipe(compress) .pipe(writeToDisk) 1 .on('error', handleErr) 2 3 .on('error', handleErr) 4 5 .on('error', handleErr) 6 7 .on('error', handleErr) 8 9 .on('error', handleErr) 10 11 .on('error', handleErr) 12 13 .on('error', handleErr) 14 Handling errors (correctly) @loige 55

readable .on('error', handleErr) .pipe(decompress) .on('error', handleErr) .pipe(decrypt) .on('error', handleErr) .pipe(convert) .on('error', handleErr) .pipe(encrypt) .on('error', handleErr) .pipe(compress) .on('error', handleErr) .pipe(writeToDisk) .on('error', handleErr) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 readable .pipe(decompress) .pipe(decrypt) .pipe(convert) .pipe(encrypt) .pipe(compress) .pipe(writeToDisk) 1 .on('error', handleErr) 2 3 .on('error', handleErr) 4 5 .on('error', handleErr) 6 7 .on('error', handleErr) 8 9 .on('error', handleErr) 10 11 .on('error', handleErr) 12 13 .on('error', handleErr) 14 .on('error', handleErr) .on('error', handleErr) .on('error', handleErr) .on('error', handleErr) .on('error', handleErr) .on('error', handleErr) .on('error', handleErr) readable 1 2 .pipe(decompress) 3 4 .pipe(decrypt) 5 6 .pipe(convert) 7 8 .pipe(encrypt) 9 10 .pipe(compress) 11 12 .pipe(writeToDisk) 13 14 Handling errors (correctly) @loige handleErr should end and destroy the streams (it doesn't happen automatically) 55

readable .on('error', handleErr) .pipe(decompress) .on('error', handleErr) .pipe(decrypt) .on('error', handleErr) .pipe(convert) .on('error', handleErr) .pipe(encrypt) .on('error', handleErr) .pipe(compress) .on('error', handleErr) .pipe(writeToDisk) .on('error', handleErr) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 readable .pipe(decompress) .pipe(decrypt) .pipe(convert) .pipe(encrypt) .pipe(compress) .pipe(writeToDisk) 1 .on('error', handleErr) 2 3 .on('error', handleErr) 4 5 .on('error', handleErr) 6 7 .on('error', handleErr) 8 9 .on('error', handleErr) 10 11 .on('error', handleErr) 12 13 .on('error', handleErr) 14 .on('error', handleErr) .on('error', handleErr) .on('error', handleErr) .on('error', handleErr) .on('error', handleErr) .on('error', handleErr) .on('error', handleErr) readable 1 2 .pipe(decompress) 3 4 .pipe(decrypt) 5 6 .pipe(convert) 7 8 .pipe(encrypt) 9 10 .pipe(compress) 11 12 .pipe(writeToDisk) 13 14 Handling errors (correctly) @loige handleErr should end and destroy the streams (it doesn't happen automatically) 55

04. STREAM UTILITIES 04. STREAM UTILITIES @loige 56

// stream-copy-gzip-pipeline.js const { pipeline } = require('stream') const { createReadStream, createWriteStream } = require('fs') const { createGzip } = require('zlib') const [, , src, dest] = process.argv pipeline( createReadStream(src), createGzip(), createWriteStream(dest), function onEnd (err) { if (err) { console.error(`Error: ${err}`) process.exit(1) } console.log('Done!') } ) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 stream.pipeline(...streams, callback) - Node.js 10+ @loige 57

// stream-copy-gzip-pipeline.js const { pipeline } = require('stream') const { createReadStream, createWriteStream } = require('fs') const { createGzip } = require('zlib') const [, , src, dest] = process.argv pipeline( createReadStream(src), createGzip(), createWriteStream(dest), function onEnd (err) { if (err) { console.error(`Error: ${err}`) process.exit(1) } console.log('Done!') } ) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 const { pipeline } = require('stream') pipeline( ) // stream-copy-gzip-pipeline.js 1 2 3 const { createReadStream, createWriteStream } = require('fs') 4 const { createGzip } = require('zlib') 5 6 const [, , src, dest] = process.argv 7 8 9 createReadStream(src), 10 createGzip(), 11 createWriteStream(dest), 12 function onEnd (err) { 13 if (err) { 14 console.error(`Error: ${err}`) 15 process.exit(1) 16 } 17 18 console.log('Done!') 19 } 20 21 stream.pipeline(...streams, callback) - Node.js 10+ @loige 57

// stream-copy-gzip-pipeline.js const { pipeline } = require('stream') const { createReadStream, createWriteStream } = require('fs') const { createGzip } = require('zlib') const [, , src, dest] = process.argv pipeline( createReadStream(src), createGzip(), createWriteStream(dest), function onEnd (err) { if (err) { console.error(`Error: ${err}`) process.exit(1) } console.log('Done!') } ) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 const { pipeline } = require('stream') pipeline( ) // stream-copy-gzip-pipeline.js 1 2 3 const { createReadStream, createWriteStream } = require('fs') 4 const { createGzip } = require('zlib') 5 6 const [, , src, dest] = process.argv 7 8 9 createReadStream(src), 10 createGzip(), 11 createWriteStream(dest), 12 function onEnd (err) { 13 if (err) { 14 console.error(`Error: ${err}`) 15 process.exit(1) 16 } 17 18 console.log('Done!') 19 } 20 21 createReadStream(src), createGzip(), createWriteStream(dest), // stream-copy-gzip-pipeline.js 1 2 const { pipeline } = require('stream') 3 const { createReadStream, createWriteStream } = require('fs') 4 const { createGzip } = require('zlib') 5 6 const [, , src, dest] = process.argv 7 8 pipeline( 9 10 11 12 function onEnd (err) { 13 if (err) { 14 console.error(`Error: ${err}`) 15 process.exit(1) 16 } 17 18 console.log('Done!') 19 } 20 ) 21 stream.pipeline(...streams, callback) - Node.js 10+ @loige You can pass multiple streams (they will be piped) 57

// stream-copy-gzip-pipeline.js const { pipeline } = require('stream') const { createReadStream, createWriteStream } = require('fs') const { createGzip } = require('zlib') const [, , src, dest] = process.argv pipeline( createReadStream(src), createGzip(), createWriteStream(dest), function onEnd (err) { if (err) { console.error(`Error: ${err}`) process.exit(1) } console.log('Done!') } ) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 const { pipeline } = require('stream') pipeline( ) // stream-copy-gzip-pipeline.js 1 2 3 const { createReadStream, createWriteStream } = require('fs') 4 const { createGzip } = require('zlib') 5 6 const [, , src, dest] = process.argv 7 8 9 createReadStream(src), 10 createGzip(), 11 createWriteStream(dest), 12 function onEnd (err) { 13 if (err) { 14 console.error(`Error: ${err}`) 15 process.exit(1) 16 } 17 18 console.log('Done!') 19 } 20 21 createReadStream(src), createGzip(), createWriteStream(dest), // stream-copy-gzip-pipeline.js 1 2 const { pipeline } = require('stream') 3 const { createReadStream, createWriteStream } = require('fs') 4 const { createGzip } = require('zlib') 5 6 const [, , src, dest] = process.argv 7 8 pipeline( 9 10 11 12 function onEnd (err) { 13 if (err) { 14 console.error(`Error: ${err}`) 15 process.exit(1) 16 } 17 18 console.log('Done!') 19 } 20 ) 21 function onEnd (err) { } // stream-copy-gzip-pipeline.js 1 2 const { pipeline } = require('stream') 3 const { createReadStream, createWriteStream } = require('fs') 4 const { createGzip } = require('zlib') 5 6 const [, , src, dest] = process.argv 7 8 pipeline( 9 createReadStream(src), 10 createGzip(), 11 createWriteStream(dest), 12 13 if (err) { 14 console.error(`Error: ${err}`) 15 process.exit(1) 16 } 17 18 console.log('Done!') 19 20 ) 21 stream.pipeline(...streams, callback) - Node.js 10+ @loige You can pass multiple streams (they will be piped) 57

// stream-copy-gzip-pipeline.js const { pipeline } = require('stream') const { createReadStream, createWriteStream } = require('fs') const { createGzip } = require('zlib') const [, , src, dest] = process.argv pipeline( createReadStream(src), createGzip(), createWriteStream(dest), function onEnd (err) { if (err) { console.error(`Error: ${err}`) process.exit(1) } console.log('Done!') } ) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 const { pipeline } = require('stream') pipeline( ) // stream-copy-gzip-pipeline.js 1 2 3 const { createReadStream, createWriteStream } = require('fs') 4 const { createGzip } = require('zlib') 5 6 const [, , src, dest] = process.argv 7 8 9 createReadStream(src), 10 createGzip(), 11 createWriteStream(dest), 12 function onEnd (err) { 13 if (err) { 14 console.error(`Error: ${err}`) 15 process.exit(1) 16 } 17 18 console.log('Done!') 19 } 20 21 createReadStream(src), createGzip(), createWriteStream(dest), // stream-copy-gzip-pipeline.js 1 2 const { pipeline } = require('stream') 3 const { createReadStream, createWriteStream } = require('fs') 4 const { createGzip } = require('zlib') 5 6 const [, , src, dest] = process.argv 7 8 pipeline( 9 10 11 12 function onEnd (err) { 13 if (err) { 14 console.error(`Error: ${err}`) 15 process.exit(1) 16 } 17 18 console.log('Done!') 19 } 20 ) 21 function onEnd (err) { } // stream-copy-gzip-pipeline.js 1 2 const { pipeline } = require('stream') 3 const { createReadStream, createWriteStream } = require('fs') 4 const { createGzip } = require('zlib') 5 6 const [, , src, dest] = process.argv 7 8 pipeline( 9 createReadStream(src), 10 createGzip(), 11 createWriteStream(dest), 12 13 if (err) { 14 console.error(`Error: ${err}`) 15 process.exit(1) 16 } 17 18 console.log('Done!') 19 20 ) 21 if (err) { console.error(`Error: ${err}`) process.exit(1) } console.log('Done!') // stream-copy-gzip-pipeline.js 1 2 const { pipeline } = require('stream') 3 const { createReadStream, createWriteStream } = require('fs') 4 const { createGzip } = require('zlib') 5 6 const [, , src, dest] = process.argv 7 8 pipeline( 9 createReadStream(src), 10 createGzip(), 11 createWriteStream(dest), 12 function onEnd (err) { 13 14 15 16 17 18 19 } 20 ) 21 stream.pipeline(...streams, callback) - Node.js 10+ @loige You can pass multiple streams (they will be piped) The last argument is a callback. If invoked with an error, it means the pipeline failed at some point. All the streams are ended and destroyed correctly. 57

// stream-copy-gzip-pump.js const pump = require('pump') // from npm const { createReadStream, createWriteStream } = require('fs') const { createGzip } = require('zlib') const [, , src, dest] = process.argv pump( // just swap pipeline with pump! createReadStream(src), createGzip(), createWriteStream(dest), function onEnd (err) { if (err) { console.error(`Error: ${err}`) process.exit(1) } console.log('Done!') } ) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 For Node.js < 10: pump - npm.im/pump @loige 58

// stream-copy-gzip-pump.js const pump = require('pump') // from npm const { createReadStream, createWriteStream } = require('fs') const { createGzip } = require('zlib') const [, , src, dest] = process.argv pump( // just swap pipeline with pump! createReadStream(src), createGzip(), createWriteStream(dest), function onEnd (err) { if (err) { console.error(`Error: ${err}`) process.exit(1) } console.log('Done!') } ) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 const pump = require('pump') // from npm pump( // just swap pipeline with pump! ) // stream-copy-gzip-pump.js 1 2 3 const { createReadStream, createWriteStream } = require('fs') 4 const { createGzip } = require('zlib') 5 6 const [, , src, dest] = process.argv 7 8 9 createReadStream(src), 10 createGzip(), 11 createWriteStream(dest), 12 function onEnd (err) { 13 if (err) { 14 console.error(`Error: ${err}`) 15 process.exit(1) 16 } 17 18 console.log('Done!') 19 } 20 21 For Node.js < 10: pump - npm.im/pump @loige 58

pumpify(...streams) - Create reusable pieces of pipeline npm.im/pumpify @loige Let's create EncGz, an application that helps us to read and write encrypted- gzipped files 59

// encgz-stream.js - utility library const { createCipheriv, createDecipheriv, randomBytes, createHash } = require('crypto') const { createGzip, createGunzip } = require('zlib') const pumpify = require('pumpify') // from npm // calculates md5 of the secret (trimmed) function getChiperKey (secret) {} function createEncgz (secret) { const initVect = randomBytes(16) const cipherKey = getChiperKey(secret) const encryptStream = createCipheriv('aes256', cipherKey, initVect) const gzipStream = createGzip() const stream = pumpify(encryptStream, gzipStream) stream.initVect = initVect return stream } 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 @loige 60

// encgz-stream.js - utility library const { createCipheriv, createDecipheriv, randomBytes, createHash } = require('crypto') const { createGzip, createGunzip } = require('zlib') const pumpify = require('pumpify') // from npm // calculates md5 of the secret (trimmed) function getChiperKey (secret) {} function createEncgz (secret) { const initVect = randomBytes(16) const cipherKey = getChiperKey(secret) const encryptStream = createCipheriv('aes256', cipherKey, initVect) const gzipStream = createGzip() const stream = pumpify(encryptStream, gzipStream) stream.initVect = initVect return stream } 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 function createEncgz (secret) { } // encgz-stream.js - utility library 1 2 const { 3 createCipheriv, 4 createDecipheriv, 5 randomBytes, 6 createHash 7 } = require('crypto') 8 const { createGzip, createGunzip } = require('zlib') 9 const pumpify = require('pumpify') // from npm 10 11 // calculates md5 of the secret (trimmed) 12 function getChiperKey (secret) {} 13 14 15 const initVect = randomBytes(16) 16 const cipherKey = getChiperKey(secret) 17 const encryptStream = createCipheriv('aes256', cipherKey, initVect) 18 const gzipStream = createGzip() 19 20 const stream = pumpify(encryptStream, gzipStream) 21 stream.initVect = initVect 22 23 return stream 24 25 @loige 60

// encgz-stream.js - utility library const { createCipheriv, createDecipheriv, randomBytes, createHash } = require('crypto') const { createGzip, createGunzip } = require('zlib') const pumpify = require('pumpify') // from npm // calculates md5 of the secret (trimmed) function getChiperKey (secret) {} function createEncgz (secret) { const initVect = randomBytes(16) const cipherKey = getChiperKey(secret) const encryptStream = createCipheriv('aes256', cipherKey, initVect) const gzipStream = createGzip() const stream = pumpify(encryptStream, gzipStream) stream.initVect = initVect return stream } 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 function createEncgz (secret) { } // encgz-stream.js - utility library 1 2 const { 3 createCipheriv, 4 createDecipheriv, 5 randomBytes, 6 createHash 7 } = require('crypto') 8 const { createGzip, createGunzip } = require('zlib') 9 const pumpify = require('pumpify') // from npm 10 11 // calculates md5 of the secret (trimmed) 12 function getChiperKey (secret) {} 13 14 15 const initVect = randomBytes(16) 16 const cipherKey = getChiperKey(secret) 17 const encryptStream = createCipheriv('aes256', cipherKey, initVect) 18 const gzipStream = createGzip() 19 20 const stream = pumpify(encryptStream, gzipStream) 21 stream.initVect = initVect 22 23 return stream 24 25 const encryptStream = createCipheriv('aes256', cipherKey, initVect) const gzipStream = createGzip() // encgz-stream.js - utility library 1 2 const { 3 createCipheriv, 4 createDecipheriv, 5 randomBytes, 6 createHash 7 } = require('crypto') 8 const { createGzip, createGunzip } = require('zlib') 9 const pumpify = require('pumpify') // from npm 10 11 // calculates md5 of the secret (trimmed) 12 function getChiperKey (secret) {} 13 14 function createEncgz (secret) { 15 const initVect = randomBytes(16) 16 const cipherKey = getChiperKey(secret) 17 18 19 20 const stream = pumpify(encryptStream, gzipStream) 21 stream.initVect = initVect 22 23 return stream 24 } 25 @loige 60

// encgz-stream.js - utility library const { createCipheriv, createDecipheriv, randomBytes, createHash } = require('crypto') const { createGzip, createGunzip } = require('zlib') const pumpify = require('pumpify') // from npm // calculates md5 of the secret (trimmed) function getChiperKey (secret) {} function createEncgz (secret) { const initVect = randomBytes(16) const cipherKey = getChiperKey(secret) const encryptStream = createCipheriv('aes256', cipherKey, initVect) const gzipStream = createGzip() const stream = pumpify(encryptStream, gzipStream) stream.initVect = initVect return stream } 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 function createEncgz (secret) { } // encgz-stream.js - utility library 1 2 const { 3 createCipheriv, 4 createDecipheriv, 5 randomBytes, 6 createHash 7 } = require('crypto') 8 const { createGzip, createGunzip } = require('zlib') 9 const pumpify = require('pumpify') // from npm 10 11 // calculates md5 of the secret (trimmed) 12 function getChiperKey (secret) {} 13 14 15 const initVect = randomBytes(16) 16 const cipherKey = getChiperKey(secret) 17 const encryptStream = createCipheriv('aes256', cipherKey, initVect) 18 const gzipStream = createGzip() 19 20 const stream = pumpify(encryptStream, gzipStream) 21 stream.initVect = initVect 22 23 return stream 24 25 const encryptStream = createCipheriv('aes256', cipherKey, initVect) const gzipStream = createGzip() // encgz-stream.js - utility library 1 2 const { 3 createCipheriv, 4 createDecipheriv, 5 randomBytes, 6 createHash 7 } = require('crypto') 8 const { createGzip, createGunzip } = require('zlib') 9 const pumpify = require('pumpify') // from npm 10 11 // calculates md5 of the secret (trimmed) 12 function getChiperKey (secret) {} 13 14 function createEncgz (secret) { 15 const initVect = randomBytes(16) 16 const cipherKey = getChiperKey(secret) 17 18 19 20 const stream = pumpify(encryptStream, gzipStream) 21 stream.initVect = initVect 22 23 return stream 24 } 25 const stream = pumpify(encryptStream, gzipStream) // encgz-stream.js - utility library 1 2 const { 3 createCipheriv, 4 createDecipheriv, 5 randomBytes, 6 createHash 7 } = require('crypto') 8 const { createGzip, createGunzip } = require('zlib') 9 const pumpify = require('pumpify') // from npm 10 11 // calculates md5 of the secret (trimmed) 12 function getChiperKey (secret) {} 13 14 function createEncgz (secret) { 15 const initVect = randomBytes(16) 16 const cipherKey = getChiperKey(secret) 17 const encryptStream = createCipheriv('aes256', cipherKey, initVect) 18 const gzipStream = createGzip() 19 20 21 stream.initVect = initVect 22 23 return stream 24 } 25 @loige 60

// encgz-stream.js - utility library const { createCipheriv, createDecipheriv, randomBytes, createHash } = require('crypto') const { createGzip, createGunzip } = require('zlib') const pumpify = require('pumpify') // from npm // calculates md5 of the secret (trimmed) function getChiperKey (secret) {} function createEncgz (secret) { const initVect = randomBytes(16) const cipherKey = getChiperKey(secret) const encryptStream = createCipheriv('aes256', cipherKey, initVect) const gzipStream = createGzip() const stream = pumpify(encryptStream, gzipStream) stream.initVect = initVect return stream } 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 function createEncgz (secret) { } // encgz-stream.js - utility library 1 2 const { 3 createCipheriv, 4 createDecipheriv, 5 randomBytes, 6 createHash 7 } = require('crypto') 8 const { createGzip, createGunzip } = require('zlib') 9 const pumpify = require('pumpify') // from npm 10 11 // calculates md5 of the secret (trimmed) 12 function getChiperKey (secret) {} 13 14 15 const initVect = randomBytes(16) 16 const cipherKey = getChiperKey(secret) 17 const encryptStream = createCipheriv('aes256', cipherKey, initVect) 18 const gzipStream = createGzip() 19 20 const stream = pumpify(encryptStream, gzipStream) 21 stream.initVect = initVect 22 23 return stream 24 25 const encryptStream = createCipheriv('aes256', cipherKey, initVect) const gzipStream = createGzip() // encgz-stream.js - utility library 1 2 const { 3 createCipheriv, 4 createDecipheriv, 5 randomBytes, 6 createHash 7 } = require('crypto') 8 const { createGzip, createGunzip } = require('zlib') 9 const pumpify = require('pumpify') // from npm 10 11 // calculates md5 of the secret (trimmed) 12 function getChiperKey (secret) {} 13 14 function createEncgz (secret) { 15 const initVect = randomBytes(16) 16 const cipherKey = getChiperKey(secret) 17 18 19 20 const stream = pumpify(encryptStream, gzipStream) 21 stream.initVect = initVect 22 23 return stream 24 } 25 const stream = pumpify(encryptStream, gzipStream) // encgz-stream.js - utility library 1 2 const { 3 createCipheriv, 4 createDecipheriv, 5 randomBytes, 6 createHash 7 } = require('crypto') 8 const { createGzip, createGunzip } = require('zlib') 9 const pumpify = require('pumpify') // from npm 10 11 // calculates md5 of the secret (trimmed) 12 function getChiperKey (secret) {} 13 14 function createEncgz (secret) { 15 const initVect = randomBytes(16) 16 const cipherKey = getChiperKey(secret) 17 const encryptStream = createCipheriv('aes256', cipherKey, initVect) 18 const gzipStream = createGzip() 19 20 21 stream.initVect = initVect 22 23 return stream 24 } 25 return stream // encgz-stream.js - utility library 1 2 const { 3 createCipheriv, 4 createDecipheriv, 5 randomBytes, 6 createHash 7 } = require('crypto') 8 const { createGzip, createGunzip } = require('zlib') 9 const pumpify = require('pumpify') // from npm 10 11 // calculates md5 of the secret (trimmed) 12 function getChiperKey (secret) {} 13 14 function createEncgz (secret) { 15 const initVect = randomBytes(16) 16 const cipherKey = getChiperKey(secret) 17 const encryptStream = createCipheriv('aes256', cipherKey, initVect) 18 const gzipStream = createGzip() 19 20 const stream = pumpify(encryptStream, gzipStream) 21 stream.initVect = initVect 22 23 24 } 25 @loige 60

// encgz-stream.js (...continue from previous slide) function createDecgz (secret, initVect) { const cipherKey = getChiperKey(secret) const decryptStream = createDecipheriv('aes256', cipherKey, initVect) const gunzipStream = createGunzip() const stream = pumpify(gunzipStream, decryptStream) return stream } module.exports = { createEncgz, createDecgz } 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 @loige 61

// encgz-stream.js (...continue from previous slide) function createDecgz (secret, initVect) { const cipherKey = getChiperKey(secret) const decryptStream = createDecipheriv('aes256', cipherKey, initVect) const gunzipStream = createGunzip() const stream = pumpify(gunzipStream, decryptStream) return stream } module.exports = { createEncgz, createDecgz } 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 function createDecgz (secret, initVect) { } // encgz-stream.js (...continue from previous slide) 1 2 3 const cipherKey = getChiperKey(secret) 4 const decryptStream = createDecipheriv('aes256', cipherKey, initVect) 5 const gunzipStream = createGunzip() 6 7 const stream = pumpify(gunzipStream, decryptStream) 8 return stream 9 10 11 module.exports = { 12 createEncgz, 13 createDecgz 14 } 15 @loige 61

// encgz-stream.js (...continue from previous slide) function createDecgz (secret, initVect) { const cipherKey = getChiperKey(secret) const decryptStream = createDecipheriv('aes256', cipherKey, initVect) const gunzipStream = createGunzip() const stream = pumpify(gunzipStream, decryptStream) return stream } module.exports = { createEncgz, createDecgz } 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 function createDecgz (secret, initVect) { } // encgz-stream.js (...continue from previous slide) 1 2 3 const cipherKey = getChiperKey(secret) 4 const decryptStream = createDecipheriv('aes256', cipherKey, initVect) 5 const gunzipStream = createGunzip() 6 7 const stream = pumpify(gunzipStream, decryptStream) 8 return stream 9 10 11 module.exports = { 12 createEncgz, 13 createDecgz 14 } 15 const decryptStream = createDecipheriv('aes256', cipherKey, initVect) const gunzipStream = createGunzip() // encgz-stream.js (...continue from previous slide) 1 2 function createDecgz (secret, initVect) { 3 const cipherKey = getChiperKey(secret) 4 5 6 7 const stream = pumpify(gunzipStream, decryptStream) 8 return stream 9 } 10 11 module.exports = { 12 createEncgz, 13 createDecgz 14 } 15 @loige 61

// encgz-stream.js (...continue from previous slide) function createDecgz (secret, initVect) { const cipherKey = getChiperKey(secret) const decryptStream = createDecipheriv('aes256', cipherKey, initVect) const gunzipStream = createGunzip() const stream = pumpify(gunzipStream, decryptStream) return stream } module.exports = { createEncgz, createDecgz } 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 function createDecgz (secret, initVect) { } // encgz-stream.js (...continue from previous slide) 1 2 3 const cipherKey = getChiperKey(secret) 4 const decryptStream = createDecipheriv('aes256', cipherKey, initVect) 5 const gunzipStream = createGunzip() 6 7 const stream = pumpify(gunzipStream, decryptStream) 8 return stream 9 10 11 module.exports = { 12 createEncgz, 13 createDecgz 14 } 15 const decryptStream = createDecipheriv('aes256', cipherKey, initVect) const gunzipStream = createGunzip() // encgz-stream.js (...continue from previous slide) 1 2 function createDecgz (secret, initVect) { 3 const cipherKey = getChiperKey(secret) 4 5 6 7 const stream = pumpify(gunzipStream, decryptStream) 8 return stream 9 } 10 11 module.exports = { 12 createEncgz, 13 createDecgz 14 } 15 const stream = pumpify(gunzipStream, decryptStream) return stream // encgz-stream.js (...continue from previous slide) 1 2 function createDecgz (secret, initVect) { 3 const cipherKey = getChiperKey(secret) 4 const decryptStream = createDecipheriv('aes256', cipherKey, initVect) 5 const gunzipStream = createGunzip() 6 7 8 9 } 10 11 module.exports = { 12 createEncgz, 13 createDecgz 14 } 15 @loige 61

// encgz-stream.js (...continue from previous slide) function createDecgz (secret, initVect) { const cipherKey = getChiperKey(secret) const decryptStream = createDecipheriv('aes256', cipherKey, initVect) const gunzipStream = createGunzip() const stream = pumpify(gunzipStream, decryptStream) return stream } module.exports = { createEncgz, createDecgz } 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 function createDecgz (secret, initVect) { } // encgz-stream.js (...continue from previous slide) 1 2 3 const cipherKey = getChiperKey(secret) 4 const decryptStream = createDecipheriv('aes256', cipherKey, initVect) 5 const gunzipStream = createGunzip() 6 7 const stream = pumpify(gunzipStream, decryptStream) 8 return stream 9 10 11 module.exports = { 12 createEncgz, 13 createDecgz 14 } 15 const decryptStream = createDecipheriv('aes256', cipherKey, initVect) const gunzipStream = createGunzip() // encgz-stream.js (...continue from previous slide) 1 2 function createDecgz (secret, initVect) { 3 const cipherKey = getChiperKey(secret) 4 5 6 7 const stream = pumpify(gunzipStream, decryptStream) 8 return stream 9 } 10 11 module.exports = { 12 createEncgz, 13 createDecgz 14 } 15 const stream = pumpify(gunzipStream, decryptStream) return stream // encgz-stream.js (...continue from previous slide) 1 2 function createDecgz (secret, initVect) { 3 const cipherKey = getChiperKey(secret) 4 const decryptStream = createDecipheriv('aes256', cipherKey, initVect) 5 const gunzipStream = createGunzip() 6 7 8 9 } 10 11 module.exports = { 12 createEncgz, 13 createDecgz 14 } 15 module.exports = { createEncgz, createDecgz } // encgz-stream.js (...continue from previous slide) 1 2 function createDecgz (secret, initVect) { 3 const cipherKey = getChiperKey(secret) 4 const decryptStream = createDecipheriv('aes256', cipherKey, initVect) 5 const gunzipStream = createGunzip() 6 7 const stream = pumpify(gunzipStream, decryptStream) 8 return stream 9 } 10 11 12 13 14 15 @loige 61

// encgz.js - CLI to encrypt and gzip (from stdin to stdout) const { pipeline } = require('stream') const { createEncgz } = require('./encgz-stream') const [, , secret] = process.argv const encgz = createEncgz(secret) console.error(`init vector: ${encgz.initVect.toString('hex')}`) pipeline( process.stdin, encgz, process.stdout, function onEnd (err) { if (err) { console.error(`Error: ${err}`) process.exit(1) } } ) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 @loige 62

// encgz.js - CLI to encrypt and gzip (from stdin to stdout) const { pipeline } = require('stream') const { createEncgz } = require('./encgz-stream') const [, , secret] = process.argv const encgz = createEncgz(secret) console.error(`init vector: ${encgz.initVect.toString('hex')}`) pipeline( process.stdin, encgz, process.stdout, function onEnd (err) { if (err) { console.error(`Error: ${err}`) process.exit(1) } } ) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 const [, , secret] = process.argv // encgz.js - CLI to encrypt and gzip (from stdin to stdout) 1 2 const { pipeline } = require('stream') 3 const { createEncgz } = require('./encgz-stream') 4 5 6 7 const encgz = createEncgz(secret) 8 console.error(`init vector: ${encgz.initVect.toString('hex')}`) 9 10 pipeline( 11 process.stdin, 12 encgz, 13 process.stdout, 14 function onEnd (err) { 15 if (err) { 16 console.error(`Error: ${err}`) 17 process.exit(1) 18 } 19 } 20 ) 21 @loige 62

// encgz.js - CLI to encrypt and gzip (from stdin to stdout) const { pipeline } = require('stream') const { createEncgz } = require('./encgz-stream') const [, , secret] = process.argv const encgz = createEncgz(secret) console.error(`init vector: ${encgz.initVect.toString('hex')}`) pipeline( process.stdin, encgz, process.stdout, function onEnd (err) { if (err) { console.error(`Error: ${err}`) process.exit(1) } } ) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 const [, , secret] = process.argv // encgz.js - CLI to encrypt and gzip (from stdin to stdout) 1 2 const { pipeline } = require('stream') 3 const { createEncgz } = require('./encgz-stream') 4 5 6 7 const encgz = createEncgz(secret) 8 console.error(`init vector: ${encgz.initVect.toString('hex')}`) 9 10 pipeline( 11 process.stdin, 12 encgz, 13 process.stdout, 14 function onEnd (err) { 15 if (err) { 16 console.error(`Error: ${err}`) 17 process.exit(1) 18 } 19 } 20 ) 21 const encgz = createEncgz(secret) // encgz.js - CLI to encrypt and gzip (from stdin to stdout) 1 2 const { pipeline } = require('stream') 3 const { createEncgz } = require('./encgz-stream') 4 5 const [, , secret] = process.argv 6 7 8 console.error(`init vector: ${encgz.initVect.toString('hex')}`) 9 10 pipeline( 11 process.stdin, 12 encgz, 13 process.stdout, 14 function onEnd (err) { 15 if (err) { 16 console.error(`Error: ${err}`) 17 process.exit(1) 18 } 19 } 20 ) 21 @loige 62

// encgz.js - CLI to encrypt and gzip (from stdin to stdout) const { pipeline } = require('stream') const { createEncgz } = require('./encgz-stream') const [, , secret] = process.argv const encgz = createEncgz(secret) console.error(`init vector: ${encgz.initVect.toString('hex')}`) pipeline( process.stdin, encgz, process.stdout, function onEnd (err) { if (err) { console.error(`Error: ${err}`) process.exit(1) } } ) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 const [, , secret] = process.argv // encgz.js - CLI to encrypt and gzip (from stdin to stdout) 1 2 const { pipeline } = require('stream') 3 const { createEncgz } = require('./encgz-stream') 4 5 6 7 const encgz = createEncgz(secret) 8 console.error(`init vector: ${encgz.initVect.toString('hex')}`) 9 10 pipeline( 11 process.stdin, 12 encgz, 13 process.stdout, 14 function onEnd (err) { 15 if (err) { 16 console.error(`Error: ${err}`) 17 process.exit(1) 18 } 19 } 20 ) 21 const encgz = createEncgz(secret) // encgz.js - CLI to encrypt and gzip (from stdin to stdout) 1 2 const { pipeline } = require('stream') 3 const { createEncgz } = require('./encgz-stream') 4 5 const [, , secret] = process.argv 6 7 8 console.error(`init vector: ${encgz.initVect.toString('hex')}`) 9 10 pipeline( 11 process.stdin, 12 encgz, 13 process.stdout, 14 function onEnd (err) { 15 if (err) { 16 console.error(`Error: ${err}`) 17 process.exit(1) 18 } 19 } 20 ) 21 pipeline( ) // encgz.js - CLI to encrypt and gzip (from stdin to stdout) 1 2 const { pipeline } = require('stream') 3 const { createEncgz } = require('./encgz-stream') 4 5 const [, , secret] = process.argv 6 7 const encgz = createEncgz(secret) 8 console.error(`init vector: ${encgz.initVect.toString('hex')}`) 9 10 11 process.stdin, 12 encgz, 13 process.stdout, 14 function onEnd (err) { 15 if (err) { 16 console.error(`Error: ${err}`) 17 process.exit(1) 18 } 19 } 20 21 @loige 62

// encgz.js - CLI to encrypt and gzip (from stdin to stdout) const { pipeline } = require('stream') const { createEncgz } = require('./encgz-stream') const [, , secret] = process.argv const encgz = createEncgz(secret) console.error(`init vector: ${encgz.initVect.toString('hex')}`) pipeline( process.stdin, encgz, process.stdout, function onEnd (err) { if (err) { console.error(`Error: ${err}`) process.exit(1) } } ) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 const [, , secret] = process.argv // encgz.js - CLI to encrypt and gzip (from stdin to stdout) 1 2 const { pipeline } = require('stream') 3 const { createEncgz } = require('./encgz-stream') 4 5 6 7 const encgz = createEncgz(secret) 8 console.error(`init vector: ${encgz.initVect.toString('hex')}`) 9 10 pipeline( 11 process.stdin, 12 encgz, 13 process.stdout, 14 function onEnd (err) { 15 if (err) { 16 console.error(`Error: ${err}`) 17 process.exit(1) 18 } 19 } 20 ) 21 const encgz = createEncgz(secret) // encgz.js - CLI to encrypt and gzip (from stdin to stdout) 1 2 const { pipeline } = require('stream') 3 const { createEncgz } = require('./encgz-stream') 4 5 const [, , secret] = process.argv 6 7 8 console.error(`init vector: ${encgz.initVect.toString('hex')}`) 9 10 pipeline( 11 process.stdin, 12 encgz, 13 process.stdout, 14 function onEnd (err) { 15 if (err) { 16 console.error(`Error: ${err}`) 17 process.exit(1) 18 } 19 } 20 ) 21 pipeline( ) // encgz.js - CLI to encrypt and gzip (from stdin to stdout) 1 2 const { pipeline } = require('stream') 3 const { createEncgz } = require('./encgz-stream') 4 5 const [, , secret] = process.argv 6 7 const encgz = createEncgz(secret) 8 console.error(`init vector: ${encgz.initVect.toString('hex')}`) 9 10 11 process.stdin, 12 encgz, 13 process.stdout, 14 function onEnd (err) { 15 if (err) { 16 console.error(`Error: ${err}`) 17 process.exit(1) 18 } 19 } 20 21 process.stdin, encgz, process.stdout, // encgz.js - CLI to encrypt and gzip (from stdin to stdout) 1 2 const { pipeline } = require('stream') 3 const { createEncgz } = require('./encgz-stream') 4 5 const [, , secret] = process.argv 6 7 const encgz = createEncgz(secret) 8 console.error(`init vector: ${encgz.initVect.toString('hex')}`) 9 10 pipeline( 11 12 13 14 function onEnd (err) { 15 if (err) { 16 console.error(`Error: ${err}`) 17 process.exit(1) 18 } 19 } 20 ) 21 @loige 62

// decgz.js - CLI to gunzip and decrypt (from stdin to stdout) const { pipeline } = require('stream') const { createDecgz } = require('./encgz-stream') const [, , secret, initVect] = process.argv const decgz = createDecgz(secret, Buffer.from(initVect, 'hex')) pipeline( process.stdin, decgz, process.stdout, function onEnd (err) { if (err) { console.error(`Error: ${err}`) process.exit(1) } } ) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 @loige 63

// decgz.js - CLI to gunzip and decrypt (from stdin to stdout) const { pipeline } = require('stream') const { createDecgz } = require('./encgz-stream') const [, , secret, initVect] = process.argv const decgz = createDecgz(secret, Buffer.from(initVect, 'hex')) pipeline( process.stdin, decgz, process.stdout, function onEnd (err) { if (err) { console.error(`Error: ${err}`) process.exit(1) } } ) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 const [, , secret, initVect] = process.argv // decgz.js - CLI to gunzip and decrypt (from stdin to stdout) 1 2 const { pipeline } = require('stream') 3 const { createDecgz } = require('./encgz-stream') 4 5 6 7 const decgz = createDecgz(secret, Buffer.from(initVect, 'hex')) 8 9 10 pipeline( 11 process.stdin, 12 decgz, 13 process.stdout, 14 function onEnd (err) { 15 if (err) { 16 console.error(`Error: ${err}`) 17 process.exit(1) 18 } 19 } 20 ) 21 @loige 63

// decgz.js - CLI to gunzip and decrypt (from stdin to stdout) const { pipeline } = require('stream') const { createDecgz } = require('./encgz-stream') const [, , secret, initVect] = process.argv const decgz = createDecgz(secret, Buffer.from(initVect, 'hex')) pipeline( process.stdin, decgz, process.stdout, function onEnd (err) { if (err) { console.error(`Error: ${err}`) process.exit(1) } } ) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 const [, , secret, initVect] = process.argv // decgz.js - CLI to gunzip and decrypt (from stdin to stdout) 1 2 const { pipeline } = require('stream') 3 const { createDecgz } = require('./encgz-stream') 4 5 6 7 const decgz = createDecgz(secret, Buffer.from(initVect, 'hex')) 8 9 10 pipeline( 11 process.stdin, 12 decgz, 13 process.stdout, 14 function onEnd (err) { 15 if (err) { 16 console.error(`Error: ${err}`) 17 process.exit(1) 18 } 19 } 20 ) 21 const decgz = createDecgz(secret, Buffer.from(initVect, 'hex')) // decgz.js - CLI to gunzip and decrypt (from stdin to stdout) 1 2 const { pipeline } = require('stream') 3 const { createDecgz } = require('./encgz-stream') 4 5 const [, , secret, initVect] = process.argv 6 7 8 9 10 pipeline( 11 process.stdin, 12 decgz, 13 process.stdout, 14 function onEnd (err) { 15 if (err) { 16 console.error(`Error: ${err}`) 17 process.exit(1) 18 } 19 } 20 ) 21 @loige 63

// decgz.js - CLI to gunzip and decrypt (from stdin to stdout) const { pipeline } = require('stream') const { createDecgz } = require('./encgz-stream') const [, , secret, initVect] = process.argv const decgz = createDecgz(secret, Buffer.from(initVect, 'hex')) pipeline( process.stdin, decgz, process.stdout, function onEnd (err) { if (err) { console.error(`Error: ${err}`) process.exit(1) } } ) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 const [, , secret, initVect] = process.argv // decgz.js - CLI to gunzip and decrypt (from stdin to stdout) 1 2 const { pipeline } = require('stream') 3 const { createDecgz } = require('./encgz-stream') 4 5 6 7 const decgz = createDecgz(secret, Buffer.from(initVect, 'hex')) 8 9 10 pipeline( 11 process.stdin, 12 decgz, 13 process.stdout, 14 function onEnd (err) { 15 if (err) { 16 console.error(`Error: ${err}`) 17 process.exit(1) 18 } 19 } 20 ) 21 const decgz = createDecgz(secret, Buffer.from(initVect, 'hex')) // decgz.js - CLI to gunzip and decrypt (from stdin to stdout) 1 2 const { pipeline } = require('stream') 3 const { createDecgz } = require('./encgz-stream') 4 5 const [, , secret, initVect] = process.argv 6 7 8 9 10 pipeline( 11 process.stdin, 12 decgz, 13 process.stdout, 14 function onEnd (err) { 15 if (err) { 16 console.error(`Error: ${err}`) 17 process.exit(1) 18 } 19 } 20 ) 21 pipeline( ) // decgz.js - CLI to gunzip and decrypt (from stdin to stdout) 1 2 const { pipeline } = require('stream') 3 const { createDecgz } = require('./encgz-stream') 4 5 const [, , secret, initVect] = process.argv 6 7 const decgz = createDecgz(secret, Buffer.from(initVect, 'hex')) 8 9 10 11 process.stdin, 12 decgz, 13 process.stdout, 14 function onEnd (err) { 15 if (err) { 16 console.error(`Error: ${err}`) 17 process.exit(1) 18 } 19 } 20 21 @loige 63

// decgz.js - CLI to gunzip and decrypt (from stdin to stdout) const { pipeline } = require('stream') const { createDecgz } = require('./encgz-stream') const [, , secret, initVect] = process.argv const decgz = createDecgz(secret, Buffer.from(initVect, 'hex')) pipeline( process.stdin, decgz, process.stdout, function onEnd (err) { if (err) { console.error(`Error: ${err}`) process.exit(1) } } ) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 const [, , secret, initVect] = process.argv // decgz.js - CLI to gunzip and decrypt (from stdin to stdout) 1 2 const { pipeline } = require('stream') 3 const { createDecgz } = require('./encgz-stream') 4 5 6 7 const decgz = createDecgz(secret, Buffer.from(initVect, 'hex')) 8 9 10 pipeline( 11 process.stdin, 12 decgz, 13 process.stdout, 14 function onEnd (err) { 15 if (err) { 16 console.error(`Error: ${err}`) 17 process.exit(1) 18 } 19 } 20 ) 21 const decgz = createDecgz(secret, Buffer.from(initVect, 'hex')) // decgz.js - CLI to gunzip and decrypt (from stdin to stdout) 1 2 const { pipeline } = require('stream') 3 const { createDecgz } = require('./encgz-stream') 4 5 const [, , secret, initVect] = process.argv 6 7 8 9 10 pipeline( 11 process.stdin, 12 decgz, 13 process.stdout, 14 function onEnd (err) { 15 if (err) { 16 console.error(`Error: ${err}`) 17 process.exit(1) 18 } 19 } 20 ) 21 pipeline( ) // decgz.js - CLI to gunzip and decrypt (from stdin to stdout) 1 2 const { pipeline } = require('stream') 3 const { createDecgz } = require('./encgz-stream') 4 5 const [, , secret, initVect] = process.argv 6 7 const decgz = createDecgz(secret, Buffer.from(initVect, 'hex')) 8 9 10 11 process.stdin, 12 decgz, 13 process.stdout, 14 function onEnd (err) { 15 if (err) { 16 console.error(`Error: ${err}`) 17 process.exit(1) 18 } 19 } 20 21 process.stdin, decgz, process.stdout, // decgz.js - CLI to gunzip and decrypt (from stdin to stdout) 1 2 const { pipeline } = require('stream') 3 const { createDecgz } = require('./encgz-stream') 4 5 const [, , secret, initVect] = process.argv 6 7 const decgz = createDecgz(secret, Buffer.from(initVect, 'hex')) 8 9 10 pipeline( 11 12 13 14 function onEnd (err) { 15 if (err) { 16 console.error(`Error: ${err}`) 17 process.exit(1) 18 } 19 } 20 ) 21 @loige 63

@loige 64

readable-stream - Npm package that contains the latest version of Node.js stream library. It also makes Node.js streams compatible with the browser (can be used with Webpack and Broswserify) npm.im/readable-stream @loige * yeah, the name is misleading. The package offers all the functionalities in the official 'stream' package, not just readable streams. * 65

04. WRITING CUSTOM 04. WRITING CUSTOM STREAMS STREAMS @loige 66

@loige EmojiStream Uppercasify DOMAppend 67

@loige EmojiStream Uppercasify DOMAppend Lemon 67

@loige EmojiStream Uppercasify DOMAppend LEMON 67

@loige EmojiStream Uppercasify DOMAppend LEMON 67

@loige EmojiStream Uppercasify DOMAppend LEMON Banana 67

@loige EmojiStream Uppercasify DOMAppend LEMON BANANA 67

@loige EmojiStream Uppercasify DOMAppend LEMON BANANA 67

@loige EmojiStream Uppercasify DOMAppend LEMON class EmojiStream extends Readable { _read() { // ... } } BANANA 67

@loige EmojiStream Uppercasify DOMAppend LEMON class EmojiStream extends Readable { _read() { // ... } } class Uppercasify extends Transform { _transform( chunk, enc, done ) { // ... } } BANANA 67

@loige EmojiStream Uppercasify DOMAppend LEMON class EmojiStream extends Readable { _read() { // ... } } class Uppercasify extends Transform { _transform( chunk, enc, done ) { // ... } } class DOMAppend extends Writable { _write( chunk, enc, done ) { // ... } } BANANA 67

@loige EmojiStream Uppercasify DOMAppend LEMON class EmojiStream extends Readable { _read() { // ... } } class Uppercasify extends Transform { _transform( chunk, enc, done ) { // ... } } class DOMAppend extends Writable { _write( chunk, enc, done ) { // ... } } BANANA this.push(data) pass data to the next step 67

// emoji-stream.js (custom readable stream) const { EMOJI_MAP } = require('emoji') // from npm const { Readable } = require('readable-stream') // from npm const emojis = Object.keys(EMOJI_MAP) function getEmojiDescription (index) { return EMOJI_MAP[emojis[index]][1] } function getMessage (index) { return emojis[index] + ' ' + getEmojiDescription(index) } class EmojiStream extends Readable { constructor (options) { super(options) this._index = 0 } _read () { if (this._index >= emojis.length) { return this.push(null) } return this.push(getMessage(this._index++)) } } module.exports = EmojiStream 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 @loige 68

// emoji-stream.js (custom readable stream) const { EMOJI_MAP } = require('emoji') // from npm const { Readable } = require('readable-stream') // from npm const emojis = Object.keys(EMOJI_MAP) function getEmojiDescription (index) { return EMOJI_MAP[emojis[index]][1] } function getMessage (index) { return emojis[index] + ' ' + getEmojiDescription(index) } class EmojiStream extends Readable { constructor (options) { super(options) this._index = 0 } _read () { if (this._index >= emojis.length) { return this.push(null) } return this.push(getMessage(this._index++)) } } module.exports = EmojiStream 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 const { Readable } = require('readable-stream') // from npm // emoji-stream.js (custom readable stream) 1 const { EMOJI_MAP } = require('emoji') // from npm 2 3 const emojis = Object.keys(EMOJI_MAP) 4 function getEmojiDescription (index) { 5 return EMOJI_MAP[emojis[index]][1] 6 } 7 function getMessage (index) { 8 return emojis[index] + ' ' + getEmojiDescription(index) 9 } 10 11 class EmojiStream extends Readable { 12 constructor (options) { 13 super(options) 14 this._index = 0 15 } 16 17 _read () { 18 if (this._index >= emojis.length) { 19 return this.push(null) 20 } 21 return this.push(getMessage(this._index++)) 22 } 23 } 24 25 module.exports = EmojiStream 26 @loige 68

// emoji-stream.js (custom readable stream) const { EMOJI_MAP } = require('emoji') // from npm const { Readable } = require('readable-stream') // from npm const emojis = Object.keys(EMOJI_MAP) function getEmojiDescription (index) { return EMOJI_MAP[emojis[index]][1] } function getMessage (index) { return emojis[index] + ' ' + getEmojiDescription(index) } class EmojiStream extends Readable { constructor (options) { super(options) this._index = 0 } _read () { if (this._index >= emojis.length) { return this.push(null) } return this.push(getMessage(this._index++)) } } module.exports = EmojiStream 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 const { Readable } = require('readable-stream') // from npm // emoji-stream.js (custom readable stream) 1 const { EMOJI_MAP } = require('emoji') // from npm 2 3 const emojis = Object.keys(EMOJI_MAP) 4 function getEmojiDescription (index) { 5 return EMOJI_MAP[emojis[index]][1] 6 } 7 function getMessage (index) { 8 return emojis[index] + ' ' + getEmojiDescription(index) 9 } 10 11 class EmojiStream extends Readable { 12 constructor (options) { 13 super(options) 14 this._index = 0 15 } 16 17 _read () { 18 if (this._index >= emojis.length) { 19 return this.push(null) 20 } 21 return this.push(getMessage(this._index++)) 22 } 23 } 24 25 module.exports = EmojiStream 26 class EmojiStream extends Readable { } // emoji-stream.js (custom readable stream) 1 const { EMOJI_MAP } = require('emoji') // from npm 2 const { Readable } = require('readable-stream') // from npm 3 const emojis = Object.keys(EMOJI_MAP) 4 function getEmojiDescription (index) { 5 return EMOJI_MAP[emojis[index]][1] 6 } 7 function getMessage (index) { 8 return emojis[index] + ' ' + getEmojiDescription(index) 9 } 10 11 12 constructor (options) { 13 super(options) 14 this._index = 0 15 } 16 17 _read () { 18 if (this._index >= emojis.length) { 19 return this.push(null) 20 } 21 return this.push(getMessage(this._index++)) 22 } 23 24 25 module.exports = EmojiStream 26 @loige 68

// emoji-stream.js (custom readable stream) const { EMOJI_MAP } = require('emoji') // from npm const { Readable } = require('readable-stream') // from npm const emojis = Object.keys(EMOJI_MAP) function getEmojiDescription (index) { return EMOJI_MAP[emojis[index]][1] } function getMessage (index) { return emojis[index] + ' ' + getEmojiDescription(index) } class EmojiStream extends Readable { constructor (options) { super(options) this._index = 0 } _read () { if (this._index >= emojis.length) { return this.push(null) } return this.push(getMessage(this._index++)) } } module.exports = EmojiStream 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 const { Readable } = require('readable-stream') // from npm // emoji-stream.js (custom readable stream) 1 const { EMOJI_MAP } = require('emoji') // from npm 2 3 const emojis = Object.keys(EMOJI_MAP) 4 function getEmojiDescription (index) { 5 return EMOJI_MAP[emojis[index]][1] 6 } 7 function getMessage (index) { 8 return emojis[index] + ' ' + getEmojiDescription(index) 9 } 10 11 class EmojiStream extends Readable { 12 constructor (options) { 13 super(options) 14 this._index = 0 15 } 16 17 _read () { 18 if (this._index >= emojis.length) { 19 return this.push(null) 20 } 21 return this.push(getMessage(this._index++)) 22 } 23 } 24 25 module.exports = EmojiStream 26 class EmojiStream extends Readable { } // emoji-stream.js (custom readable stream) 1 const { EMOJI_MAP } = require('emoji') // from npm 2 const { Readable } = require('readable-stream') // from npm 3 const emojis = Object.keys(EMOJI_MAP) 4 function getEmojiDescription (index) { 5 return EMOJI_MAP[emojis[index]][1] 6 } 7 function getMessage (index) { 8 return emojis[index] + ' ' + getEmojiDescription(index) 9 } 10 11 12 constructor (options) { 13 super(options) 14 this._index = 0 15 } 16 17 _read () { 18 if (this._index >= emojis.length) { 19 return this.push(null) 20 } 21 return this.push(getMessage(this._index++)) 22 } 23 24 25 module.exports = EmojiStream 26 _read () { } // emoji-stream.js (custom readable stream) 1 const { EMOJI_MAP } = require('emoji') // from npm 2 const { Readable } = require('readable-stream') // from npm 3 const emojis = Object.keys(EMOJI_MAP) 4 function getEmojiDescription (index) { 5 return EMOJI_MAP[emojis[index]][1] 6 } 7 function getMessage (index) { 8 return emojis[index] + ' ' + getEmojiDescription(index) 9 } 10 11 class EmojiStream extends Readable { 12 constructor (options) { 13 super(options) 14 this._index = 0 15 } 16 17 18 if (this._index >= emojis.length) { 19 return this.push(null) 20 } 21 return this.push(getMessage(this._index++)) 22 23 } 24 25 module.exports = EmojiStream 26 @loige 68

// emoji-stream.js (custom readable stream) const { EMOJI_MAP } = require('emoji') // from npm const { Readable } = require('readable-stream') // from npm const emojis = Object.keys(EMOJI_MAP) function getEmojiDescription (index) { return EMOJI_MAP[emojis[index]][1] } function getMessage (index) { return emojis[index] + ' ' + getEmojiDescription(index) } class EmojiStream extends Readable { constructor (options) { super(options) this._index = 0 } _read () { if (this._index >= emojis.length) { return this.push(null) } return this.push(getMessage(this._index++)) } } module.exports = EmojiStream 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 const { Readable } = require('readable-stream') // from npm // emoji-stream.js (custom readable stream) 1 const { EMOJI_MAP } = require('emoji') // from npm 2 3 const emojis = Object.keys(EMOJI_MAP) 4 function getEmojiDescription (index) { 5 return EMOJI_MAP[emojis[index]][1] 6 } 7 function getMessage (index) { 8 return emojis[index] + ' ' + getEmojiDescription(index) 9 } 10 11 class EmojiStream extends Readable { 12 constructor (options) { 13 super(options) 14 this._index = 0 15 } 16 17 _read () { 18 if (this._index >= emojis.length) { 19 return this.push(null) 20 } 21 return this.push(getMessage(this._index++)) 22 } 23 } 24 25 module.exports = EmojiStream 26 class EmojiStream extends Readable { } // emoji-stream.js (custom readable stream) 1 const { EMOJI_MAP } = require('emoji') // from npm 2 const { Readable } = require('readable-stream') // from npm 3 const emojis = Object.keys(EMOJI_MAP) 4 function getEmojiDescription (index) { 5 return EMOJI_MAP[emojis[index]][1] 6 } 7 function getMessage (index) { 8 return emojis[index] + ' ' + getEmojiDescription(index) 9 } 10 11 12 constructor (options) { 13 super(options) 14 this._index = 0 15 } 16 17 _read () { 18 if (this._index >= emojis.length) { 19 return this.push(null) 20 } 21 return this.push(getMessage(this._index++)) 22 } 23 24 25 module.exports = EmojiStream 26 _read () { } // emoji-stream.js (custom readable stream) 1 const { EMOJI_MAP } = require('emoji') // from npm 2 const { Readable } = require('readable-stream') // from npm 3 const emojis = Object.keys(EMOJI_MAP) 4 function getEmojiDescription (index) { 5 return EMOJI_MAP[emojis[index]][1] 6 } 7 function getMessage (index) { 8 return emojis[index] + ' ' + getEmojiDescription(index) 9 } 10 11 class EmojiStream extends Readable { 12 constructor (options) { 13 super(options) 14 this._index = 0 15 } 16 17 18 if (this._index >= emojis.length) { 19 return this.push(null) 20 } 21 return this.push(getMessage(this._index++)) 22 23 } 24 25 module.exports = EmojiStream 26 if (this._index >= emojis.length) { } // emoji-stream.js (custom readable stream) 1 const { EMOJI_MAP } = require('emoji') // from npm 2 const { Readable } = require('readable-stream') // from npm 3 const emojis = Object.keys(EMOJI_MAP) 4 function getEmojiDescription (index) { 5 return EMOJI_MAP[emojis[index]][1] 6 } 7 function getMessage (index) { 8 return emojis[index] + ' ' + getEmojiDescription(index) 9 } 10 11 class EmojiStream extends Readable { 12 constructor (options) { 13 super(options) 14 this._index = 0 15 } 16 17 _read () { 18 19 return this.push(null) 20 21 return this.push(getMessage(this._index++)) 22 } 23 } 24 25 module.exports = EmojiStream 26 @loige 68

// emoji-stream.js (custom readable stream) const { EMOJI_MAP } = require('emoji') // from npm const { Readable } = require('readable-stream') // from npm const emojis = Object.keys(EMOJI_MAP) function getEmojiDescription (index) { return EMOJI_MAP[emojis[index]][1] } function getMessage (index) { return emojis[index] + ' ' + getEmojiDescription(index) } class EmojiStream extends Readable { constructor (options) { super(options) this._index = 0 } _read () { if (this._index >= emojis.length) { return this.push(null) } return this.push(getMessage(this._index++)) } } module.exports = EmojiStream 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 const { Readable } = require('readable-stream') // from npm // emoji-stream.js (custom readable stream) 1 const { EMOJI_MAP } = require('emoji') // from npm 2 3 const emojis = Object.keys(EMOJI_MAP) 4 function getEmojiDescription (index) { 5 return EMOJI_MAP[emojis[index]][1] 6 } 7 function getMessage (index) { 8 return emojis[index] + ' ' + getEmojiDescription(index) 9 } 10 11 class EmojiStream extends Readable { 12 constructor (options) { 13 super(options) 14 this._index = 0 15 } 16 17 _read () { 18 if (this._index >= emojis.length) { 19 return this.push(null) 20 } 21 return this.push(getMessage(this._index++)) 22 } 23 } 24 25 module.exports = EmojiStream 26 class EmojiStream extends Readable { } // emoji-stream.js (custom readable stream) 1 const { EMOJI_MAP } = require('emoji') // from npm 2 const { Readable } = require('readable-stream') // from npm 3 const emojis = Object.keys(EMOJI_MAP) 4 function getEmojiDescription (index) { 5 return EMOJI_MAP[emojis[index]][1] 6 } 7 function getMessage (index) { 8 return emojis[index] + ' ' + getEmojiDescription(index) 9 } 10 11 12 constructor (options) { 13 super(options) 14 this._index = 0 15 } 16 17 _read () { 18 if (this._index >= emojis.length) { 19 return this.push(null) 20 } 21 return this.push(getMessage(this._index++)) 22 } 23 24 25 module.exports = EmojiStream 26 _read () { } // emoji-stream.js (custom readable stream) 1 const { EMOJI_MAP } = require('emoji') // from npm 2 const { Readable } = require('readable-stream') // from npm 3 const emojis = Object.keys(EMOJI_MAP) 4 function getEmojiDescription (index) { 5 return EMOJI_MAP[emojis[index]][1] 6 } 7 function getMessage (index) { 8 return emojis[index] + ' ' + getEmojiDescription(index) 9 } 10 11 class EmojiStream extends Readable { 12 constructor (options) { 13 super(options) 14 this._index = 0 15 } 16 17 18 if (this._index >= emojis.length) { 19 return this.push(null) 20 } 21 return this.push(getMessage(this._index++)) 22 23 } 24 25 module.exports = EmojiStream 26 if (this._index >= emojis.length) { } // emoji-stream.js (custom readable stream) 1 const { EMOJI_MAP } = require('emoji') // from npm 2 const { Readable } = require('readable-stream') // from npm 3 const emojis = Object.keys(EMOJI_MAP) 4 function getEmojiDescription (index) { 5 return EMOJI_MAP[emojis[index]][1] 6 } 7 function getMessage (index) { 8 return emojis[index] + ' ' + getEmojiDescription(index) 9 } 10 11 class EmojiStream extends Readable { 12 constructor (options) { 13 super(options) 14 this._index = 0 15 } 16 17 _read () { 18 19 return this.push(null) 20 21 return this.push(getMessage(this._index++)) 22 } 23 } 24 25 module.exports = EmojiStream 26 return this.push(null) // emoji-stream.js (custom readable stream) 1 const { EMOJI_MAP } = require('emoji') // from npm 2 const { Readable } = require('readable-stream') // from npm 3 const emojis = Object.keys(EMOJI_MAP) 4 function getEmojiDescription (index) { 5 return EMOJI_MAP[emojis[index]][1] 6 } 7 function getMessage (index) { 8 return emojis[index] + ' ' + getEmojiDescription(index) 9 } 10 11 class EmojiStream extends Readable { 12 constructor (options) { 13 super(options) 14 this._index = 0 15 } 16 17 _read () { 18 if (this._index >= emojis.length) { 19 20 } 21 return this.push(getMessage(this._index++)) 22 } 23 } 24 25 module.exports = EmojiStream 26 @loige 68

// emoji-stream.js (custom readable stream) const { EMOJI_MAP } = require('emoji') // from npm const { Readable } = require('readable-stream') // from npm const emojis = Object.keys(EMOJI_MAP) function getEmojiDescription (index) { return EMOJI_MAP[emojis[index]][1] } function getMessage (index) { return emojis[index] + ' ' + getEmojiDescription(index) } class EmojiStream extends Readable { constructor (options) { super(options) this._index = 0 } _read () { if (this._index >= emojis.length) { return this.push(null) } return this.push(getMessage(this._index++)) } } module.exports = EmojiStream 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 const { Readable } = require('readable-stream') // from npm // emoji-stream.js (custom readable stream) 1 const { EMOJI_MAP } = require('emoji') // from npm 2 3 const emojis = Object.keys(EMOJI_MAP) 4 function getEmojiDescription (index) { 5 return EMOJI_MAP[emojis[index]][1] 6 } 7 function getMessage (index) { 8 return emojis[index] + ' ' + getEmojiDescription(index) 9 } 10 11 class EmojiStream extends Readable { 12 constructor (options) { 13 super(options) 14 this._index = 0 15 } 16 17 _read () { 18 if (this._index >= emojis.length) { 19 return this.push(null) 20 } 21 return this.push(getMessage(this._index++)) 22 } 23 } 24 25 module.exports = EmojiStream 26 class EmojiStream extends Readable { } // emoji-stream.js (custom readable stream) 1 const { EMOJI_MAP } = require('emoji') // from npm 2 const { Readable } = require('readable-stream') // from npm 3 const emojis = Object.keys(EMOJI_MAP) 4 function getEmojiDescription (index) { 5 return EMOJI_MAP[emojis[index]][1] 6 } 7 function getMessage (index) { 8 return emojis[index] + ' ' + getEmojiDescription(index) 9 } 10 11 12 constructor (options) { 13 super(options) 14 this._index = 0 15 } 16 17 _read () { 18 if (this._index >= emojis.length) { 19 return this.push(null) 20 } 21 return this.push(getMessage(this._index++)) 22 } 23 24 25 module.exports = EmojiStream 26 _read () { } // emoji-stream.js (custom readable stream) 1 const { EMOJI_MAP } = require('emoji') // from npm 2 const { Readable } = require('readable-stream') // from npm 3 const emojis = Object.keys(EMOJI_MAP) 4 function getEmojiDescription (index) { 5 return EMOJI_MAP[emojis[index]][1] 6 } 7 function getMessage (index) { 8 return emojis[index] + ' ' + getEmojiDescription(index) 9 } 10 11 class EmojiStream extends Readable { 12 constructor (options) { 13 super(options) 14 this._index = 0 15 } 16 17 18 if (this._index >= emojis.length) { 19 return this.push(null) 20 } 21 return this.push(getMessage(this._index++)) 22 23 } 24 25 module.exports = EmojiStream 26 if (this._index >= emojis.length) { } // emoji-stream.js (custom readable stream) 1 const { EMOJI_MAP } = require('emoji') // from npm 2 const { Readable } = require('readable-stream') // from npm 3 const emojis = Object.keys(EMOJI_MAP) 4 function getEmojiDescription (index) { 5 return EMOJI_MAP[emojis[index]][1] 6 } 7 function getMessage (index) { 8 return emojis[index] + ' ' + getEmojiDescription(index) 9 } 10 11 class EmojiStream extends Readable { 12 constructor (options) { 13 super(options) 14 this._index = 0 15 } 16 17 _read () { 18 19 return this.push(null) 20 21 return this.push(getMessage(this._index++)) 22 } 23 } 24 25 module.exports = EmojiStream 26 return this.push(null) // emoji-stream.js (custom readable stream) 1 const { EMOJI_MAP } = require('emoji') // from npm 2 const { Readable } = require('readable-stream') // from npm 3 const emojis = Object.keys(EMOJI_MAP) 4 function getEmojiDescription (index) { 5 return EMOJI_MAP[emojis[index]][1] 6 } 7 function getMessage (index) { 8 return emojis[index] + ' ' + getEmojiDescription(index) 9 } 10 11 class EmojiStream extends Readable { 12 constructor (options) { 13 super(options) 14 this._index = 0 15 } 16 17 _read () { 18 if (this._index >= emojis.length) { 19 20 } 21 return this.push(getMessage(this._index++)) 22 } 23 } 24 25 module.exports = EmojiStream 26 return this.push(getMessage(this._index++)) // emoji-stream.js (custom readable stream) 1 const { EMOJI_MAP } = require('emoji') // from npm 2 const { Readable } = require('readable-stream') // from npm 3 const emojis = Object.keys(EMOJI_MAP) 4 function getEmojiDescription (index) { 5 return EMOJI_MAP[emojis[index]][1] 6 } 7 function getMessage (index) { 8 return emojis[index] + ' ' + getEmojiDescription(index) 9 } 10 11 class EmojiStream extends Readable { 12 constructor (options) { 13 super(options) 14 this._index = 0 15 } 16 17 _read () { 18 if (this._index >= emojis.length) { 19 return this.push(null) 20 } 21 22 } 23 } 24 25 module.exports = EmojiStream 26 @loige 68

// uppercasify.js (custom transform stream) const { Transform } = require('readable-stream') class Uppercasify extends Transform { _transform (chunk, encoding, done) { this.push(chunk.toString().toUpperCase()) done() } } module.exports = Uppercasify 1 2 3 4 5 6 7 8 9 10 11 12 @loige 69

// uppercasify.js (custom transform stream) const { Transform } = require('readable-stream') class Uppercasify extends Transform { _transform (chunk, encoding, done) { this.push(chunk.toString().toUpperCase()) done() } } module.exports = Uppercasify 1 2 3 4 5 6 7 8 9 10 11 12 const { Transform } = require('readable-stream') // uppercasify.js (custom transform stream) 1 2 3 4 class Uppercasify extends Transform { 5 _transform (chunk, encoding, done) { 6 this.push(chunk.toString().toUpperCase()) 7 done() 8 } 9 } 10 11 module.exports = Uppercasify 12 @loige 69

// uppercasify.js (custom transform stream) const { Transform } = require('readable-stream') class Uppercasify extends Transform { _transform (chunk, encoding, done) { this.push(chunk.toString().toUpperCase()) done() } } module.exports = Uppercasify 1 2 3 4 5 6 7 8 9 10 11 12 const { Transform } = require('readable-stream') // uppercasify.js (custom transform stream) 1 2 3 4 class Uppercasify extends Transform { 5 _transform (chunk, encoding, done) { 6 this.push(chunk.toString().toUpperCase()) 7 done() 8 } 9 } 10 11 module.exports = Uppercasify 12 class Uppercasify extends Transform { } // uppercasify.js (custom transform stream) 1 2 const { Transform } = require('readable-stream') 3 4 5 _transform (chunk, encoding, done) { 6 this.push(chunk.toString().toUpperCase()) 7 done() 8 } 9 10 11 module.exports = Uppercasify 12 @loige 69

// uppercasify.js (custom transform stream) const { Transform } = require('readable-stream') class Uppercasify extends Transform { _transform (chunk, encoding, done) { this.push(chunk.toString().toUpperCase()) done() } } module.exports = Uppercasify 1 2 3 4 5 6 7 8 9 10 11 12 const { Transform } = require('readable-stream') // uppercasify.js (custom transform stream) 1 2 3 4 class Uppercasify extends Transform { 5 _transform (chunk, encoding, done) { 6 this.push(chunk.toString().toUpperCase()) 7 done() 8 } 9 } 10 11 module.exports = Uppercasify 12 class Uppercasify extends Transform { } // uppercasify.js (custom transform stream) 1 2 const { Transform } = require('readable-stream') 3 4 5 _transform (chunk, encoding, done) { 6 this.push(chunk.toString().toUpperCase()) 7 done() 8 } 9 10 11 module.exports = Uppercasify 12 _transform (chunk, encoding, done) { } // uppercasify.js (custom transform stream) 1 2 const { Transform } = require('readable-stream') 3 4 class Uppercasify extends Transform { 5 6 this.push(chunk.toString().toUpperCase()) 7 done() 8 9 } 10 11 module.exports = Uppercasify 12 @loige 69

// uppercasify.js (custom transform stream) const { Transform } = require('readable-stream') class Uppercasify extends Transform { _transform (chunk, encoding, done) { this.push(chunk.toString().toUpperCase()) done() } } module.exports = Uppercasify 1 2 3 4 5 6 7 8 9 10 11 12 const { Transform } = require('readable-stream') // uppercasify.js (custom transform stream) 1 2 3 4 class Uppercasify extends Transform { 5 _transform (chunk, encoding, done) { 6 this.push(chunk.toString().toUpperCase()) 7 done() 8 } 9 } 10 11 module.exports = Uppercasify 12 class Uppercasify extends Transform { } // uppercasify.js (custom transform stream) 1 2 const { Transform } = require('readable-stream') 3 4 5 _transform (chunk, encoding, done) { 6 this.push(chunk.toString().toUpperCase()) 7 done() 8 } 9 10 11 module.exports = Uppercasify 12 _transform (chunk, encoding, done) { } // uppercasify.js (custom transform stream) 1 2 const { Transform } = require('readable-stream') 3 4 class Uppercasify extends Transform { 5 6 this.push(chunk.toString().toUpperCase()) 7 done() 8 9 } 10 11 module.exports = Uppercasify 12 this.push(chunk.toString().toUpperCase()) // uppercasify.js (custom transform stream) 1 2 const { Transform } = require('readable-stream') 3 4 class Uppercasify extends Transform { 5 _transform (chunk, encoding, done) { 6 7 done() 8 } 9 } 10 11 module.exports = Uppercasify 12 @loige 69

// uppercasify.js (custom transform stream) const { Transform } = require('readable-stream') class Uppercasify extends Transform { _transform (chunk, encoding, done) { this.push(chunk.toString().toUpperCase()) done() } } module.exports = Uppercasify 1 2 3 4 5 6 7 8 9 10 11 12 const { Transform } = require('readable-stream') // uppercasify.js (custom transform stream) 1 2 3 4 class Uppercasify extends Transform { 5 _transform (chunk, encoding, done) { 6 this.push(chunk.toString().toUpperCase()) 7 done() 8 } 9 } 10 11 module.exports = Uppercasify 12 class Uppercasify extends Transform { } // uppercasify.js (custom transform stream) 1 2 const { Transform } = require('readable-stream') 3 4 5 _transform (chunk, encoding, done) { 6 this.push(chunk.toString().toUpperCase()) 7 done() 8 } 9 10 11 module.exports = Uppercasify 12 _transform (chunk, encoding, done) { } // uppercasify.js (custom transform stream) 1 2 const { Transform } = require('readable-stream') 3 4 class Uppercasify extends Transform { 5 6 this.push(chunk.toString().toUpperCase()) 7 done() 8 9 } 10 11 module.exports = Uppercasify 12 this.push(chunk.toString().toUpperCase()) // uppercasify.js (custom transform stream) 1 2 const { Transform } = require('readable-stream') 3 4 class Uppercasify extends Transform { 5 _transform (chunk, encoding, done) { 6 7 done() 8 } 9 } 10 11 module.exports = Uppercasify 12 done() // uppercasify.js (custom transform stream) 1 2 const { Transform } = require('readable-stream') 3 4 class Uppercasify extends Transform { 5 _transform (chunk, encoding, done) { 6 this.push(chunk.toString().toUpperCase()) 7 8 } 9 } 10 11 module.exports = Uppercasify 12 @loige 69

// dom-append.js (custom writable stream) const { Writable } = require('readable-stream') class DOMAppend extends Writable { _write (chunk, encoding, done) { const elem = document.createElement('li') const content = document.createTextNode(chunk.toString()) elem.appendChild(content) document.getElementById('list').appendChild(elem) done() } } module.exports = DOMAppend 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 @loige 70

// dom-append.js (custom writable stream) const { Writable } = require('readable-stream') class DOMAppend extends Writable { _write (chunk, encoding, done) { const elem = document.createElement('li') const content = document.createTextNode(chunk.toString()) elem.appendChild(content) document.getElementById('list').appendChild(elem) done() } } module.exports = DOMAppend 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 const { Writable } = require('readable-stream') // dom-append.js (custom writable stream) 1 2 3 4 class DOMAppend extends Writable { 5 6 _write (chunk, encoding, done) { 7 const elem = document.createElement('li') 8 const content = document.createTextNode(chunk.toString()) 9 elem.appendChild(content) 10 document.getElementById('list').appendChild(elem) 11 done() 12 } 13 } 14 15 module.exports = DOMAppend 16 @loige 70

// dom-append.js (custom writable stream) const { Writable } = require('readable-stream') class DOMAppend extends Writable { _write (chunk, encoding, done) { const elem = document.createElement('li') const content = document.createTextNode(chunk.toString()) elem.appendChild(content) document.getElementById('list').appendChild(elem) done() } } module.exports = DOMAppend 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 const { Writable } = require('readable-stream') // dom-append.js (custom writable stream) 1 2 3 4 class DOMAppend extends Writable { 5 6 _write (chunk, encoding, done) { 7 const elem = document.createElement('li') 8 const content = document.createTextNode(chunk.toString()) 9 elem.appendChild(content) 10 document.getElementById('list').appendChild(elem) 11 done() 12 } 13 } 14 15 module.exports = DOMAppend 16 class DOMAppend extends Writable { } // dom-append.js (custom writable stream) 1 2 const { Writable } = require('readable-stream') 3 4 5 6 _write (chunk, encoding, done) { 7 const elem = document.createElement('li') 8 const content = document.createTextNode(chunk.toString()) 9 elem.appendChild(content) 10 document.getElementById('list').appendChild(elem) 11 done() 12 } 13 14 15 module.exports = DOMAppend 16 @loige 70

// dom-append.js (custom writable stream) const { Writable } = require('readable-stream') class DOMAppend extends Writable { _write (chunk, encoding, done) { const elem = document.createElement('li') const content = document.createTextNode(chunk.toString()) elem.appendChild(content) document.getElementById('list').appendChild(elem) done() } } module.exports = DOMAppend 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 const { Writable } = require('readable-stream') // dom-append.js (custom writable stream) 1 2 3 4 class DOMAppend extends Writable { 5 6 _write (chunk, encoding, done) { 7 const elem = document.createElement('li') 8 const content = document.createTextNode(chunk.toString()) 9 elem.appendChild(content) 10 document.getElementById('list').appendChild(elem) 11 done() 12 } 13 } 14 15 module.exports = DOMAppend 16 class DOMAppend extends Writable { } // dom-append.js (custom writable stream) 1 2 const { Writable } = require('readable-stream') 3 4 5 6 _write (chunk, encoding, done) { 7 const elem = document.createElement('li') 8 const content = document.createTextNode(chunk.toString()) 9 elem.appendChild(content) 10 document.getElementById('list').appendChild(elem) 11 done() 12 } 13 14 15 module.exports = DOMAppend 16 _write (chunk, encoding, done) { } // dom-append.js (custom writable stream) 1 2 const { Writable } = require('readable-stream') 3 4 class DOMAppend extends Writable { 5 6 7 const elem = document.createElement('li') 8 const content = document.createTextNode(chunk.toString()) 9 elem.appendChild(content) 10 document.getElementById('list').appendChild(elem) 11 done() 12 13 } 14 15 module.exports = DOMAppend 16 @loige 70

// dom-append.js (custom writable stream) const { Writable } = require('readable-stream') class DOMAppend extends Writable { _write (chunk, encoding, done) { const elem = document.createElement('li') const content = document.createTextNode(chunk.toString()) elem.appendChild(content) document.getElementById('list').appendChild(elem) done() } } module.exports = DOMAppend 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 const { Writable } = require('readable-stream') // dom-append.js (custom writable stream) 1 2 3 4 class DOMAppend extends Writable { 5 6 _write (chunk, encoding, done) { 7 const elem = document.createElement('li') 8 const content = document.createTextNode(chunk.toString()) 9 elem.appendChild(content) 10 document.getElementById('list').appendChild(elem) 11 done() 12 } 13 } 14 15 module.exports = DOMAppend 16 class DOMAppend extends Writable { } // dom-append.js (custom writable stream) 1 2 const { Writable } = require('readable-stream') 3 4 5 6 _write (chunk, encoding, done) { 7 const elem = document.createElement('li') 8 const content = document.createTextNode(chunk.toString()) 9 elem.appendChild(content) 10 document.getElementById('list').appendChild(elem) 11 done() 12 } 13 14 15 module.exports = DOMAppend 16 _write (chunk, encoding, done) { } // dom-append.js (custom writable stream) 1 2 const { Writable } = require('readable-stream') 3 4 class DOMAppend extends Writable { 5 6 7 const elem = document.createElement('li') 8 const content = document.createTextNode(chunk.toString()) 9 elem.appendChild(content) 10 document.getElementById('list').appendChild(elem) 11 done() 12 13 } 14 15 module.exports = DOMAppend 16 const elem = document.createElement('li') const content = document.createTextNode(chunk.toString()) elem.appendChild(content) document.getElementById('list').appendChild(elem) // dom-append.js (custom writable stream) 1 2 const { Writable } = require('readable-stream') 3 4 class DOMAppend extends Writable { 5 6 _write (chunk, encoding, done) { 7 8 9 10 11 done() 12 } 13 } 14 15 module.exports = DOMAppend 16 @loige 70

// dom-append.js (custom writable stream) const { Writable } = require('readable-stream') class DOMAppend extends Writable { _write (chunk, encoding, done) { const elem = document.createElement('li') const content = document.createTextNode(chunk.toString()) elem.appendChild(content) document.getElementById('list').appendChild(elem) done() } } module.exports = DOMAppend 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 const { Writable } = require('readable-stream') // dom-append.js (custom writable stream) 1 2 3 4 class DOMAppend extends Writable { 5 6 _write (chunk, encoding, done) { 7 const elem = document.createElement('li') 8 const content = document.createTextNode(chunk.toString()) 9 elem.appendChild(content) 10 document.getElementById('list').appendChild(elem) 11 done() 12 } 13 } 14 15 module.exports = DOMAppend 16 class DOMAppend extends Writable { } // dom-append.js (custom writable stream) 1 2 const { Writable } = require('readable-stream') 3 4 5 6 _write (chunk, encoding, done) { 7 const elem = document.createElement('li') 8 const content = document.createTextNode(chunk.toString()) 9 elem.appendChild(content) 10 document.getElementById('list').appendChild(elem) 11 done() 12 } 13 14 15 module.exports = DOMAppend 16 _write (chunk, encoding, done) { } // dom-append.js (custom writable stream) 1 2 const { Writable } = require('readable-stream') 3 4 class DOMAppend extends Writable { 5 6 7 const elem = document.createElement('li') 8 const content = document.createTextNode(chunk.toString()) 9 elem.appendChild(content) 10 document.getElementById('list').appendChild(elem) 11 done() 12 13 } 14 15 module.exports = DOMAppend 16 const elem = document.createElement('li') const content = document.createTextNode(chunk.toString()) elem.appendChild(content) document.getElementById('list').appendChild(elem) // dom-append.js (custom writable stream) 1 2 const { Writable } = require('readable-stream') 3 4 class DOMAppend extends Writable { 5 6 _write (chunk, encoding, done) { 7 8 9 10 11 done() 12 } 13 } 14 15 module.exports = DOMAppend 16 done() // dom-append.js (custom writable stream) 1 2 const { Writable } = require('readable-stream') 3 4 class DOMAppend extends Writable { 5 6 _write (chunk, encoding, done) { 7 const elem = document.createElement('li') 8 const content = document.createTextNode(chunk.toString()) 9 elem.appendChild(content) 10 document.getElementById('list').appendChild(elem) 11 12 } 13 } 14 15 module.exports = DOMAppend 16 @loige 70

05. STREAMS IN THE 05. STREAMS IN THE BROWSER BROWSER @loige 71

// browser/app.js const EmojiStream = require('../emoji-stream') const Uppercasify = require('../uppercasify') const DOMAppend = require('../dom-append') const emoji = new EmojiStream() const uppercasify = new Uppercasify() const append = new DOMAppend() emoji .pipe(uppercasify) .pipe(append) 1 2 3 4 5 6 7 8 9 10 11 12 13 @loige 72

// browser/app.js const EmojiStream = require('../emoji-stream') const Uppercasify = require('../uppercasify') const DOMAppend = require('../dom-append') const emoji = new EmojiStream() const uppercasify = new Uppercasify() const append = new DOMAppend() emoji .pipe(uppercasify) .pipe(append) 1 2 3 4 5 6 7 8 9 10 11 12 13 const EmojiStream = require('../emoji-stream') const Uppercasify = require('../uppercasify') const DOMAppend = require('../dom-append') // browser/app.js 1 2 3 4 5 6 const emoji = new EmojiStream() 7 const uppercasify = new Uppercasify() 8 const append = new DOMAppend() 9 10 emoji 11 .pipe(uppercasify) 12 .pipe(append) 13 @loige 72

// browser/app.js const EmojiStream = require('../emoji-stream') const Uppercasify = require('../uppercasify') const DOMAppend = require('../dom-append') const emoji = new EmojiStream() const uppercasify = new Uppercasify() const append = new DOMAppend() emoji .pipe(uppercasify) .pipe(append) 1 2 3 4 5 6 7 8 9 10 11 12 13 const EmojiStream = require('../emoji-stream') const Uppercasify = require('../uppercasify') const DOMAppend = require('../dom-append') // browser/app.js 1 2 3 4 5 6 const emoji = new EmojiStream() 7 const uppercasify = new Uppercasify() 8 const append = new DOMAppend() 9 10 emoji 11 .pipe(uppercasify) 12 .pipe(append) 13 const emoji = new EmojiStream() const uppercasify = new Uppercasify() const append = new DOMAppend() // browser/app.js 1 2 const EmojiStream = require('../emoji-stream') 3 const Uppercasify = require('../uppercasify') 4 const DOMAppend = require('../dom-append') 5 6 7 8 9 10 emoji 11 .pipe(uppercasify) 12 .pipe(append) 13 @loige 72

// browser/app.js const EmojiStream = require('../emoji-stream') const Uppercasify = require('../uppercasify') const DOMAppend = require('../dom-append') const emoji = new EmojiStream() const uppercasify = new Uppercasify() const append = new DOMAppend() emoji .pipe(uppercasify) .pipe(append) 1 2 3 4 5 6 7 8 9 10 11 12 13 const EmojiStream = require('../emoji-stream') const Uppercasify = require('../uppercasify') const DOMAppend = require('../dom-append') // browser/app.js 1 2 3 4 5 6 const emoji = new EmojiStream() 7 const uppercasify = new Uppercasify() 8 const append = new DOMAppend() 9 10 emoji 11 .pipe(uppercasify) 12 .pipe(append) 13 const emoji = new EmojiStream() const uppercasify = new Uppercasify() const append = new DOMAppend() // browser/app.js 1 2 const EmojiStream = require('../emoji-stream') 3 const Uppercasify = require('../uppercasify') 4 const DOMAppend = require('../dom-append') 5 6 7 8 9 10 emoji 11 .pipe(uppercasify) 12 .pipe(append) 13 emoji .pipe(uppercasify) .pipe(append) // browser/app.js 1 2 const EmojiStream = require('../emoji-stream') 3 const Uppercasify = require('../uppercasify') 4 const DOMAppend = require('../dom-append') 5 6 const emoji = new EmojiStream() 7 const uppercasify = new Uppercasify() 8 const append = new DOMAppend() 9 10 11 12 13 @loige 72

npm i --save-dev webpack webpack-cli node_modules/.bin/webpack src/browser/app.js # creates dist/main.js mv dist/main.js src/browser/app-bundle.js @loige Let's use webpack to build this app for the browser 73

Streams in the browser!

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 @loige Finally let's create an index.html 74

Streams in the browser!

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1 2 3 4 8 Streams in the browser! 9 10 11 12 13 14 15 @loige Finally let's create an index.html 74

Streams in the browser!

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1 2 3 4 8 Streams in the browser! 9 10 11 12 13 14 15 1 2 3 4 8 Streams in the browser! 9 10 11

12 13 14 15 @loige Finally let's create an index.html 74

@loige 75

@loige 75

06. CLOSING 06. CLOSING @loige 76

Streams have low memory footprint Process data as soon as it's available Composition through pipelines Streams are abstractions: Readable = Input Transform = Business Logic Writable = Output @loige TLDR; TLDR; 77

IF YOU WANT TO LEARN (EVEN) MOAR IF YOU WANT TO LEARN (EVEN) MOAR ABOUT STREAMS... ABOUT STREAMS... nodejs.org/api/stream.html github.com/substack/stream-handbook @loige 78

IF YOU ARE NOT CONVINCED YET... IF YOU ARE NOT CONVINCED YET... @loige curl parrot.live 79

@loige github.com/hugomd/parrot.live Check out the codebase 80

@loige 81

@loige ДЯКУЮ ДЯКУЮ! ! loige.link/streams-kyiv We are hiring, talk to me! :) 82

CREDITS CREDITS Cover picture by on for the amazing St. Patrick emoji art The internet for the memes! :D Johny Goerend Unsplash emojiart.org SPECIAL THANKS SPECIAL THANKS , , , , , @StefanoAbalsamo @mariocasciaro @machine_person @Podgeypoos79 @katavic_d @UrsoLuca @loige 83