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![© 2016 Ross Kukulinski
Functions are Closures
22
function calculateSum (list) {
var sum = 0;
function addItem(item) {
sum += item;
}
list.forEach(addItem);
console.log('sum: ' + sum);
}
calculateSum([ 2, 5, 10, 42, 67, 78, 89, 120 ]);](https://image.slidesharecdn.com/ftw16introtonode-160504184122/75/Philly-Tech-Week-Introduction-to-NodeJS-22-2048.jpg)
![© 2016 Ross Kukulinski
Functions are Closures
23
function calculateSum (list) {
var sum = 0;
function addItem(item) {
sum += item;
}
list.forEach(addItem);
return function() { // return a function that can print the result
console.log('sum: ' + sum);
}
}
var printSum = calculateSum([ 2, 5, 10, 42, 67, 78, 89, 120 ]);
// printSum is a function returned by calculateSum but it still
// has access to the scope within its parent function
printSum();](https://image.slidesharecdn.com/ftw16introtonode-160504184122/75/Philly-Tech-Week-Introduction-to-NodeJS-23-2048.jpg)
Uploaded byRoss Kukulinski
Philly Tech Week Introduction to NodeJS
The document summarizes an introductory workshop on Node.js. It outlines the schedule, which includes an overview of Node.js, hands-on exercises, and pair programming lessons. The workshop aims to teach attendees what Node.js is, how its non-blocking and event-driven model works, and prepare them for future learning. It also discusses why JavaScript and its features make it well-suited for Node.js' asynchronous programming approach.
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Philly Tech Week Introduction to NodeJS
- 1. May 4, 2016 #PTW16Intro to Node.JS Ross Kukulinski
- 2. © 2016 RossKukulinski2 @RossKukulinski Product Manager — NodeSource Node Foundation Evangelist Container Advocate & Consultant Introduction to CoreOS - O’Reilly Media
- 3. © 2016 RossKukulinski Overview 3 phillydev.org #ptw-nodejs-workshop
- 4. © 2016 RossKukulinski Overview 4 Why are you here?
- 5. © 2016 RossKukulinski Overview 5 Workshop Goals • Learn what Node.JS is and is not • Understand non-blocking I/O and event-driven programming • Hands on with Node.JS! • Prepare you for future Node.JS learning
- 6. © 2016 RossKukulinski Overview 6 Schedule • 9:00 - 9:05 — Intro & Overview • 9:05 - 9:45 — What is Node.JS • 9:45 - 10:00 — Hands-on with NodeJS • 10:00 - 10:30 — NodeSchool Pair-Programming • 10:30 - 10:45 — Coffee Refill • 10:45 - 11:00 — Questions / Review • 11:00 - 11:45 — Continued Pair-Programming • 11:45 - 12:00 — Wrap up & Summary
- 7. © 2016 RossKukulinski What is Node.JS 7
- 8. © 2016 RossKukulinski8
- 9. © 2016 RossKukulinski What is Node.JS 9 Node.JS is a JavaScript runtime built on Chrome’s JavaScript engine* for building fast, scalable network applications.
- 10. © 2016 RossKukulinski Node.JS is NOT 10 … a language … a web framework
- 11. © 2016 RossKukulinski What is Node.JS 11 Node by the Numbers • Node.JS is the fastest growing development platform • 3.5 million users and annual growth rate of 100% • npm is the largest ecosystem of open source libraries in the world https://nodejs.org/static/documents/2016-survey-report.pdf
- 12. © 2016 RossKukulinski What is Node.JS 12 Enterprises have already adopted Node.js
- 13. © 2016 RossKukulinski Why does Node.JS exist? 13
- 14. © 2016 RossKukulinski Why does Node.JS Exist? 14 Latency: Memory vs I/O L1 cache 0.5ns L2 cache 7ns Main memory 100ns Send 1K bytes over 1 Gbps network 10,000ns Round trip within same datacenter 500,000ns Disk seek 10,000,000ns Packet CA->Netherlands->CA 150,000,000ns https://gist.github.com/jhclark/2845836
- 15. © 2016 RossKukulinski15 I/O is Expensive Why does Node.JS Exist?
- 16. © 2016 RossKukulinski16 console.log('Fetching article...'); var result = query("SELECT * FROM articles WHERE id = 1"); console.log('Here is the result:', result); Blocking I/O Blocking vs Non-Blocking
- 17. © 2016 RossKukulinski17 1 // Java: Spot the I/O 2 3 System.out.println("Reading file..."); 4 BufferedReader br = new BufferedReader(new 5 FileReader("in.txt")); 6 7 try { 8 StringBuilder sb = new StringBuilder(); 9 String line; 10 11 while ((line = br.readLine()) != null) 12 sb.append(line + "n"); 13 System.out.print(sb.toString()); 14 } finally { 15 br.close(); 16 } 17 18 System.out.println("Finished reading file!");
- 18. © 2016 RossKukulinski18 Some solutions • One process per connection (Apache Web Server 1) • One thread per connection (Apache Web Server 2) • Event-Driven (nginx, node.js) Blocking vs Non-Blocking
- 19. © 2016 RossKukulinski Event-Driven, Non-Blocking Programming 19 function handleResult(result) { console.log('Here is the result:', result); } select('SELECT * FROM articles WHERE id = 1', handleResult); console.log('Fetching article...');
- 20. © 2016 RossKukulinski Why JavaScript? 20 JavaScript well-suited to event-driven model
- 21. © 2016 RossKukulinski Functions are First-Class Objects 21 Treat functions like any other object • Pass them as arguments • Return them from functions • Store them as variables for later use
- 22. © 2016 RossKukulinski Functions are Closures 22 function calculateSum (list) { var sum = 0; function addItem(item) { sum += item; } list.forEach(addItem); console.log('sum: ' + sum); } calculateSum([ 2, 5, 10, 42, 67, 78, 89, 120 ]);
- 23. © 2016 RossKukulinski Functions are Closures 23 function calculateSum (list) { var sum = 0; function addItem(item) { sum += item; } list.forEach(addItem); return function() { // return a function that can print the result console.log('sum: ' + sum); } } var printSum = calculateSum([ 2, 5, 10, 42, 67, 78, 89, 120 ]); // printSum is a function returned by calculateSum but it still // has access to the scope within its parent function printSum();
- 24. © 2016 RossKukulinski Node.JS Non-Blocking I/O 24 • Kernel-level non-blocking socket I/O using epoll() or select() system calls (depending on the operating system) • File system I/O delegated to worker threads • Glued together with an “event loop”
- 25. © 2016 RossKukulinski Node.JS Event Loop 25 • Perform work triggered by JavaScript code • Perform work triggered by external events • Pass events & data to JavaScript via callback functions • Exit when no more pending work or events
- 26. © 2016 RossKukulinski Node.JS Event Loop 26 When does it stop? // 1. fs.readFile('bigdata.txt', 'utf8', function (err, data) { console.log(data.split('n').length, 'lines of data'); });
- 27. © 2016 RossKukulinski Node.JS Event Loop 27 When does it stop? // 2. setTimeout(function () { console.log('Waited 10s'); }, 10000);
- 28. © 2016 RossKukulinski Node.JS Event Loop 28 When does it stop? // 3. var i = 0; var timer = setInterval(function () { console.log('tick', i); if (++i === 60) clearInterval(timer); }, 1000);
- 29. © 2016 RossKukulinski Blocking the event loop 29 // some Monte Carlo madness // estimating π by plotting *many* random points on a plane var points = 100000000; var inside = 0; for (var i = 0; i < points; i++) { if (Math.pow(Math.random(), 2) + Math.pow(Math.random(), 2) <= 1) inside++; } // the event loop is blocked until the calculations are done console.log(‘π ≈ ’, (inside / points) * 4);
- 30. © 2016 RossKukulinski Sync vs Async 30 var bigdata = fs.readFileSync('bigdata', 'utf8'); fs.readFile('bigdata', 'utf8', function (err, bigdata) { // ... }); Synchronous Asynchronous
- 31. © 2016 RossKukulinski Node.JS Summary 31 Rules of Thumb • Choose asynchronous I/O over synchronous I/O • Opt for parallel I/O wherever possible • Don’t hog the JavaScript thread with long-running calculations or iterations
- 32. © 2016 RossKukulinski Node.JS Summary 32 Node.JS is Minimal • Complexity is in user-land • Instead of a big framework, Node.JS provides minimal viable library for doing I/O • All the rest is built on top in user-land • Pick and choose from HUGE library of third-party modules
- 33. © 2016 RossKukulinski npm - Node Package Manger 33 https://www.npmjs.com/ 250,000+ packages of reusable code
- 34. © 2016 RossKukulinski Node.JS Strengths 34 Node is great for: • REST APIs • Mobile Backend • Real-time applications • Streaming services • Prototyping • Front-end development
- 35. © 2016 RossKukulinski Node.JS Weaknesses 35 Node is NOT good for: • CPU-bound workloads • Serving static content
- 36. © 2016 RossKukulinski Hands-on with Node.JS 36
- 37. © 2016 RossKukulinski Installing Node.JS 37 https://nodejs.org/en/download/ https://github.com/creationix/nvm OSX/Linux Windows
- 38. © 2016 RossKukulinski38 What do you get? • node — The Node.JS runtime binary • npm — CLI tool allows you to use the extensive module ecosystem Installing Node.JS
- 39. © 2016 RossKukulinski Example Code 39 github.com/rosskukulinski/ptw16_node
- 40. © 2016 RossKukulinski Hands-on with NodeJS 40 Live demo time!
- 41. © 2016 RossKukulinski NodeSchool Pair-Programming 41
- 42. © 2016 RossKukulinski NodeSchool.io 42 Workshoppers Open source lesson modules to teach JavaScript, Node.JS, npm, and many more topics. All lessons are self-guided and most work offline.
- 43. © 2016 RossKukulinski43 Find a Partner! NodeSchool.io
- 44. © 2016 RossKukulinski learnyounode 44 Getting started 1. npm install -g learnyounode 2. Make a folder to store your code 3. learnyounode
- 45. © 2016 RossKukulinski learnyounode 45 Let’s work through the first exercise together
- 46. © 2016 RossKukulinski Break time! Back at 10:45 46
- 47. © 2016 RossKukulinski Questions / Review 47
- 48. © 2016 RossKukulinski Back to it! 48
- 49. © 2016 RossKukulinski Wrap Up 49
- 50. © 2016 RossKukulinski Wrap Up 50 Resources for future learning • http://nodeschool.io • https://nodejs.org/api/ • https://github.com/nodejs/help • #node.js on irc.freenode.net • http://nodeweekly.com/ • http://planetnodejs.com/ • http://nodeup.com/ • http://stackoverflow.com/questions/tagged/node.js • http://www.meetup.com/nodejs-philly/
- 51. © 2016 RossKukulinski Wrap Up 51 Package recommendations • Logging: Bunyan, winston • Webserver: Express, hapi, kraken • REST APIs: restify, hapi • Testing: mocha, tap, jasmine • Frontend: browserify, gulp, grunt, webpack • Real-time: socket.io, ws Also experiment with functional programming (Node.JS Streams)
- 52. © 2016 RossKukulinski Wrap Up 52 Want to get involved? • https://nodejs.org/en/get-involved/ • Help with documentation • Contribute to Node Core • Contribute to npm modules • Run your own NodeSchool
- 53. © 2016 RossKukulinski NodeSource 53 The Enterprise Node Company™ https://nodesource.com
- 54. © 2016 RossKukulinski NodeSource 54 N|Solid: Enterprise Grade Node • Production Monitoring • Performance Analysis • Platform Security • Free for Development
- 55.