What is Node.js
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Node.js is a JavaScript runtime built on Chrome's V8 JavaScript engine that allows JavaScript to be run on the server side. It uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, especially for real-time applications with many simultaneous connections. Node.js can be used for anything from building chat servers and analytics backends to developing full-stack web applications. While it is not a web framework itself, modules like Express allow it to function as one. Node.js runs in a single thread using an event loop to handle asynchronous callbacks instead of blocking on I/O, making it highly scalable.
What is Node.js
- 1. Node .js
- 2. WHO AM I ? • An Engineering Student at the International Institute of Technology • Node.js Developer • Article Writer at CodeProject.com
- 3. What is Node? • A powerful platform to let you run JS on the server side • How? Uses Google’s V8 Engine • V8 is built in C • V8 is the fatest JS Engine on the planet • Great way to build modern web apps on both Client and Server side!
- 4. What Can I Do in Node? • Anything you want! • Chat servers, Analytics & Crazy fast backends • Socket.io library is a wicked way to build real time apps • Build a social Network! LinkedIn, Dropbox all using Node.js
- 5. What Can’t I Do in Node? • Contradicts previous slide but Node.js is not a web framework i.e Sinatra Modules for node.js make it into web framework i.e Express Node.js is not Multi-threaded A single thread to rule them all
- 6. Non-Blocking? Blocking? I’m so confused • By introducing callbacks. Node can move on to other requests and whenever the callback is called, node will process is. • You should read non-blocking code as « put function and params in queue and fire callback when you reach the end of the queue » • Blocking= return Non-Blocking= no return. Only callbacks
- 7. Node.js runs on the event loop • The event loop keeps on running. Checking for new events, so it can call callbacks for those events. • Lets take a look at an example.
- 8. Event Loop Example var http = require('http'); http.createServer(function (request, response) { response.writeHead(200);// HTTP status response.write(‘Droidcon Tunisia') response.end(); }); server.listen(8080);
- 9. Using Events • So we saw in our example, whenever an HTTP request event is fired,our callback is called. • Node.js has a LOT of events. Lots and Lots! • Lets see some in action.
- 10. Events Example var http = require('http'); http.createServer(); server.on(‘request’,function(request,response) { response.writeHead(200);// HTTP status response.write(‘Droidcon Tunisia') response.end(); }); Server.on(‘connection’,function(socket){ Console.log(‘New Connection’); }); server.listen(8080);
- 11. Using Modules • You might have noticed we’ve been using require(‘ ’) a lot. • Require is basically a way to import modules to your application. Modules are basically classes. • They are a module of code that contain functions which have been exported. • Exported functions are basically public.
- 12. Using Modules • What does require return then? The file ? • Well no, when you require a module.It returns a JS Object. In require(‘http’) it return the HTTP object. • This has functions you can call,as well as public variables