Node.js essentials
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This document introduces Node.js, an open-source, cross-platform development platform created in 2009, highlighting its lightweight and fast nature due to C/C++ code and its event-driven, non-blocking I/O model. It discusses when to use Node.js, its core concepts such as event loops, blocking vs non-blocking I/O, and the use of modules and npm for package management. Additionally, it lists prominent users of Node.js and features frameworks like Express.js and Socket.io for building web applications and real-time applications.
![Installing a NPM module
npm install
npm install <tarball file>
npm install <tarball url>
npm install <name>
npm install <name>@<tag>
npm install <name>@<version>
npm install <name> [--save|--save-dev]
Install modules into local node_modules directory
If a module requires another module to operate, NPM will download
automatically!](https://image.slidesharecdn.com/preznodejs-161204172843/85/Node-js-essentials-28-320.jpg)
Node.js essentials
- 1. node essentials.js Made with by @elacheche_bedis
- 2. About me Bedis ElAcheche (@elacheche_bedis) - Lazy web & mobile developer - Official Ubuntu Member - FOSS lover - Javascript fanatic - Im writing bugs into apps since 2008
- 3. What to expect ahead.. - Data types - Variables - Conditional statements - Loops - Functions - Comments
- 4. What to expect ahead..
- 5. What to expect ahead (for real)... - Introduction - Event loops - Blocking and nonblocking I/O - Modules - NPM - Demos - Random memes
- 6. What is Node.js? - Open source, cross platform development platform. - A command line tool. - Created by Ryan Dahl in 2009. - Uses v8 JavaScript engine. - Uses an event-driven, non-blocking I/O model.
- 7. Why Node.js? - Free - Open source - Very lightweight and fast because it's mostly C/C++ code. - Can handle thousands of concurrent connections with minimal overhead (CPU/Memory). - There are lots of modules available for free.
- 8. When to use Node.js? - HTTP servers. - Chat applications. - Online games. - Collaboration tools. - Desktop applications. - If you are great at writing javascript code.
- 9. When not to use Node.js? - Heavy and CPU intensive calculations on server side. - Node.js is single thread - You have to write logic by your own to utilize multi core processor and make it multi threaded.
- 10. Who uses Node.js? - LinkedIn - Microsoft - Netflix - PayPal - SAP - Walmart - Uber - ...
- 11. Event loops - The core of event-driven programming. - Almost all the UI programs use event loops to track the user event. - Register callbacks for events. - Your callback is eventually red.鍖
- 12. Event loops $('a').click(function() { console.log('clicked!'); }); $.get('slides.php', { from: 1, to: 5 }, function(data) { console.log('New slides!'); });
- 13. Event loops life cycle Event loop (single thread) Register callback Trigger callback Operation complete Requests File System Database Network
- 14. Event loops life cycle - Initialize empty event loop. - Execute non-I/O code. - Add every I/O call to the event loop. - End of source code reached. - Event loop starts iterating over a list of events and callbacks. - Perform I/O using non-blocking kernel facilities. - Event loop goes to sleep. - Kernel noti es the event loop.鍖 - Event loop executes and removes a callback. - Program exits when event loop is empty.
- 15. Blocking and nonblocking I/O // Blocking I/O var attendees = db.query('SELECT * FROM attendees'); // Wait for result! attendees.each(function(attendee) { var attendeeName = attendee.getName(); // Wait for result! sayHello(attendeeName); // Wait }); startWorkshop(); // Execution is blocked!
- 16. Blocking and nonblocking I/O // Nonblocking I/O db.query('SELECT * FROM attendees', function(attendees) { attendees.each(function(attendee) { attendee.getName(function(attendeeName) { sayHello(attendeeName); }); }); }); startWorkshop(); // Executes without any delay!
- 17. Blocking and nonblocking I/O
- 18. Events in Node.js - An action detected by the program that may be handled by the program. - Determine which function will be called next. - Many objects in node emit events. - You can create objects that emit events too.
- 19. Events in Node.js // Custom event emitters var EventEmitter = require('events'); var logger = new EventEmitter(); logger.on('new-attendee', function(message) { console.log('Welcome %s! Please have a seat.', message); }); logger.on('attendee-left', function(message) { console.log('Goodbye %s! See you next time.', message); }); logger.emit('new-attendee', 'John Doe'); // Welcome John Doe! Please have a seat. logger.emit('new-attendee', 'Jane Doe'); // Welcome Jane Doe! Please have a seat. logger.emit('attendee-left', 'John Smith'); // Goodbye John Smith! See you next time.
- 21. Node.js modules - External libraries. - One kind of package which can be published to NPM. - Node.js heavily relies on modules. - Creating a module is easy, just put your javascript code in a separate js file and include it in your code by using keyword require.
- 22. Node.js modules /* Hello world */ var aModule = require('module1'); var otherModule = require('module2'); /* Awesome code */ /* Cool stuff */ app.js ./node_modules module1.js module2.js
- 23. Node.js modules // greetings.js var hello = function() { console.log('Hello %s!', name || ''); } var bye = function() { console.log('Bye %s!', name || ''); } module.exports = { hello: hello, bye: bye }; // hola.js module.exports = function(name) { console.log('Hola %s!', name || ''); }; // app.js var greetings = require('./greetings'); var hola = require('./hola'); greetings.hello(); // Hello! hola('John doe'); // Hola Jane doe! // If we only need to call once require('./greetings').bye('Jane'); // Goodbye Jane!
- 24. Node.js modules
- 25. Node.js modules How does require return the libraries?// look in same directory var awesomeModule = require('./awesome-module') // look in parent directory var awesomeModule = require('../awesome-module') // look in specific directory var awesomeModule = require('/home/d4rk-5c0rp/lab/awesome-module'); // app.js located under /home/d4rk-5c0rp/lab/nodeWorkshop var awesomeModule = require('awesome-module'); // search in node_modules directories // /home/d4rk-5c0rp/lab/nodeWorkshop/node_modules // /home/d4rk-5c0rp/lab/node_modules // /home/d4rk-5c0rp/node_modules // /home/node_modules // /node_modules
- 26. NPM - Package manager for node. - Comes bundled with Node.js installation. - Command line client that interacts with a remote registry. - Allows users to consume and distribute JavaScript modules. - Manage packages that are local dependencies of a particular project. - Manage as well globally-installed JavaScript tools.
- 27. NPM registry - Kind of an App store for developers. - There are a whole lot of modules and tools available to make the process of building programs quicker and simpler. - Look up the functionality you want, and hopefully found a module that does it for you.
- 28. Installing a NPM module npm install npm install <tarball file> npm install <tarball url> npm install <name> npm install <name>@<tag> npm install <name>@<version> npm install <name> [--save|--save-dev] Install modules into local node_modules directory If a module requires another module to operate, NPM will download automatically!
- 29. Installing a NPM module npm install gulp -g Install modules with executables globally Global NPM modules CANT be required var gulp = require('gulp'); // Error: Cannot find module 'gulp'
- 30. Express.js - Minimal and flexible Node.js framework. - Free and open-source. - Designed for building web applications and APIs.
- 31. Express.js
- 32. Socket.IO - Realtime application framework. - Enables bidirectional event-based communication. - It has two parts: a client-side library that runs in the browser, and a server-side library for Node.js.
- 33. Socket.IO
- 34. slides.emit('Thank you!'); Made with by @elacheche_bedis