<%- title %>

Project Structure We will be making a two-page website which should be enough to get us started. The first page would be our home page (index.ejs) and that would be the page with the sidebar. The second page would be the About page (about.ejs) and that would take a full with. node app.js> => to start a project 📂 node_modules 📂 public 📂 css 📜 main.css 📂 views 🌍 about.ejs 🌍 index.ejs 📂 layouts 🌍 full-width.ejs 🌍 sidebar.ejs 📂 partials 🌍 header.ejs 🌍 footer.ejs 📜 README.md 🌍 app.js 📜 package-lock.json 📜 package-json Let’s build our app.js JavaScript // Imports const express = require('express') const expressLayouts = require('express-ejs-layouts') const app = express() const port = 5000 || process.env.PORT // Static Files app.use(express.static('public')) // Example for other folders - not required // app.use('/css', express.static(__dirname + 'public/css')) // Set Templating Engine app.use(expressLayouts) app.set('layout', './layouts/full-width') app.set('view engine', 'ejs') // Routes app.get('', (req, res) => { res.render('index', { title: 'Home Page'}) }) app.get('/about', (req, res) => { res.render('about', { title: 'About Page', layout: './layouts/sidebar' }) }) // Listen on Port 5000 app.listen(port, () => console.info(`App listening on port ${port}`)) ===========>layout full width ejs <%- title %>

<%- include('../partials/header.ejs') %>

<%- body %>

<%- include('../partials/footer.ejs') %>

===========>sidebar.ejs <%- title %>

<%- include('../partials/header.ejs') %> <%- include('../partials/footer.ejs') %>

Now that we have the layouts and the CSS let’s add the partials: ==========>header.ejs

Header

==========>footer.ejs ==========>index.ejs

This is the home page and it takes the full width of the layout

About ==========>about.ejs

This is the about page. Look it has two columns.

This is a second paragraph and we can use normal html

Home Is Node.js A Programming Language? Ans:In a word: no. Node.js is not a programming language. Rather, it’s a runtime environment that’s used to run JavaScript outside the browser. Node.js is neither a programming language nor a framework; it’s an environment for them. Note:(A framework is a platform for developing software applications). =========>Is Node.js Frontend Or Backend? A common misconception among developers is that Node.js is a backend framework and is only used for building servers. This isn’t true: Node.js can be used both on the frontend and the backend. One of the reasons Node.js frameworks are a popular choice for developers building a flexible and scalable backend is its event-driven, non-blocking nature Node.js is written in C, C++, and JavaScript. Wikipedia defines Node.js as “a packaged compilation of Google’s V8 JavaScript engine, the libuv platform abstraction layer, and a core library, which is itself primarily written in JavaScript.” The runtime uses Chrome V8 internally, which is the JavaScript execution engine, and it’s also written in C++. This adds additional use cases to Node.js’s repertoire, such as accessing internal system functionality (like networking). =======>Node.js Architecture and How It Works Node.js uses the “Single Threaded Event Loop” architecture to handle multiple clients at the same time. To understand how this is different from other runtimes, we need to understand how multi-threaded concurrent clients are handled in languages like Java In a multi-threaded request-response model, multiple clients send a request, and the server processes each one before sending the response back. However, multiple threads are used to process concurrent calls. These threads are defined in a thread pool, and each time a request comes in, an individual thread is assigned to handle it. Node.js works differently. Let’s take a look at each step it goes through: Node.js maintains a limited thread pool to serve requests. Whenever a request comes, Node.js places it into a queue. Now, the single-threaded “Event loop”—the core component—comes into the picture. This event loop waits for requests indefinitely. When a request comes in, the loop picks it up from the queue and checks whether it requires a blocking input/output (I/O) operation. If not, it processes the request and sends a response. If the request has a blocking operation to perform, the event loop assigns a thread from the internal thread pool to process the request. There are limited internal threads available. This group of auxiliary threads is called the worker group. The event loop tracks blocking requests and places them in the queue once the blocking task is processed. This is how it maintains its non-blocking nature. Since Node.js uses fewer threads, it utilizes fewer resources/memory, resulting in faster task execution. So for our purposes, this single-threaded architecture is equivalent to multi-threaded architecture. When one needs to process data-intensive tasks, then using multi-threaded languages like Java makes much more sense. But for real-time applications, Node.js is the obvious choice. Features Of Node.js Node.js has grown quickly in the last few years. This is thanks to the vast list of features it provides: Easy—Node.js is quite easy to start with. It’s a go-to choice for web development beginners. With a lot of tutorials and a large community—getting started is very easy. Scalable—It provides vast scalability for applications. Node.js, being single-threaded, is capable of handling a huge number of simultaneous connections with high throughput. Speed—Non-blocking thread execution makes Node.js even faster and more efficient. Packages—A vast set of open-source Node.js packages is available that can simplify your work. There are more than one million packages in the NPM ecosystem today. Strong backend—Node.js is written in C and C++, which makes it speedy and adds features like networking support. Multi-platform—Cross-platform support allows you to create SaaS websites, desktop apps, and even mobile apps, all using Node.js. Maintainable—Node.js is an easy choice for developers since both the frontend and backend can be managed with JavaScript as a single language. Market Size Market Size There has been immense growth in websites in the last 2 decades, and as expected, Node.js is growing fast as well. The popular runtime already crossed the 1-billion download threshold back in 2018, and according to W3Techs, Node.js is used by 1.2% of all websites everywhere. That’s over 20 million total sites across the internet. Not surprisingly, it’s a popular selection with millions of companies, too. Here are a few popular ones that use Node.js today: Twitter Spotify eBay Reddit LinkedIn Godaddy Applications Of Node.js Node.js is used for a wide variety of applications. Let’s explore some popular use cases where Node.js is a good choice: Real-time chats—Due to its single-threaded asynchronous nature, Node.js is well-suited to processing real-time communication. It can easily scale and is often used in building chatbots. Node.js also makes it simple to build additional chat features like multi-person chat and push notifications. Internet of Things—IoT applications usually comprise multiple sensors, as they frequently send small chunks of data that can pile into a large number of requests. Node.js is a good choice since it’s able to handle these concurrent requests quickly. Data streaming—Companies like Netflix use Node.js for streaming purposes. This is mainly due to Node.js being lightweight and fast, besides which Node.js provides a native streaming API. These streams allow users to pipe requests to each other, resulting in data being streamed directly to its final destination. Complex single-page applications (SPAs)—In SPAs, the whole application is loaded in a single page. This usually means there are a couple of requests made in the background for specific components. Node.js’s event loop comes to the rescue here, as it processes requests in a non-blocking fashion. REST API-based applications—JavaScript is used both in the frontend and backend of sites. Thus, a server can easily communicate with the frontend via REST APIs using Node.js. Node.js also provides packages like Express.js and Koa that make it even easier to build web applications. What Is NPM? NPM is Node.js’s package ecosystem. It is the largest ecosystem of all open-source libraries in the world, with over 1 million packages and growing. NPM is free to use, and thousands of open source developers contribute to it daily. NPM comes with a command-line utility out-of-box. You can simply head over to the NPM website to search for the package you need, and install it using a single command. You can also manage your package’s versions, review dependencies, and even set up custom scripts in your projects through this command-line utility. Without a doubt, NPM is the most-loved possession of the Node.js community; Node.js attracts a large number of developers due largely to its excellent package support. Popular Packages Here are some of the most popular packages for Node.js today: Express – Express.js, or simply Express, is a Sinatra-inspired web development framework for Node.js, and the de-facto standard for the majority of Node.js applications out there today. MongoDB – The official driver to MongoDB. It provides the API for MongoDB object databases in Node.js. Socket.io – Socket enables real-time, bidirectional, and event-based communication. Lodash – Lodash makes JavaScript easier by taking the hassle out of working with arrays, numbers, objects, strings, etc. Moment – A JavaScript date library for parsing, validating, manipulating, and formatting dates. Commander.js – This is all you need to work and build with command-line interfaces for node.js. Forever – A simple CLI tool for ensuring that a given script runs continuously (i.e. forever). Keeps your Node.js process up in production in the face of any unexpected failures. Async – A utility module that provides straightforward, powerful functions for working with asynchronous JavaScript. Redis – A client library for supporting Redis database integration. Mocha – A clean, flexible JavaScript test framework for Node.js and the browser. Passport – Simple, unobtrusive authentication for Node.js. Passport’s sole purpose is to authenticate requests. Some examples of node js 1) var http = require('http'); var dt = require('./myfirstmodule'); http.createServer(function (req, res) { res.writeHead(200, {'Content-Type': 'text/html'}); res.write("The date and time are currently: " + dt.myDateTime()); res.end(); }).listen(8080); 2) var http = require('http'); var fs = require('fs'); http.createServer(function (req, res) { fs.readFile('demofile1.html', function(err, data) { res.writeHead(200, {'Content-Type': 'text/html'}); res.write(data); return res.end(); }); }).listen(8080); Commands to run Nodejs file in cmd node filename Example-node app.js To install a new package npm install packagename npm install Upper-Case To create a node project use the command: npm init