The Hypertext Transfer Protocol (HTTP) methods are used to establish communications between clients and servers.Between a client and server, the HTTP methods work as a request-response protocol. A Web browser is a client program that uses HTTP (Hypertext Transfer Protocol) to make requests of Web servers throughout the Internet on behalf of the user. For example, a client submits an HTTP request to the server, and the server returns the response to the client. The HTTP methods are identified by the requested URI(Uniform Resource Identifier). The methods are case-sensitive and these are used in uppercase. Basically, there are two common...

Express.js is a Javascript framework based on Node.js, that supports development both on the server side and the user side. Express is a very fast, essential, assertive, and moderate web framework of Node.js. You can assume express as a tier built on the top of the Node.js that helps in managing server and routes. It provides a robust set of features to develop a web application and mobile applications. It is lightweight Framework of node.js. Express provides a minimal interface to build our applications. It provides the tools that are required to build our app. It is flexible as there are numerous modules...

In Express.js, we will learn how to start and use the Express Framework of node.js. To start with node.js, you should have the Node.js and the npm (node package manager) installed. If you don’t have these package, go to the Node setup to install node on your local system. Topics Covered Node Package Manager Install Express Install Global Package Install Local Package Uninstall Modules By running the following commands in your terminal, confirm that node and npm are successfully installed on your system. node --version npm --version You should get the similar output :  C:\Users\Pankaj\Desktop\express demo>node --versionv 4.2.3 C:\Users\Pankaj\Desktop\express demo>npm...

Buffer acts as a temporary storage for a chunk of data that is to be transferred from one place to another. What buffers Actually does in Node js First of all, the buffer is filled with data, then after that, it is being passed along.Buffer collects small Chunks of data at a time.Instead of waiting for all of the data to be stored in memory what we do we transfer small chunks of data in a buffer and buffer collects small chunks of data and when the buffer is full, we pass that chunk of data down the stream it...

Topics Covered:- What is template engine? How to use Template Engine? Sending variables to EJS and show on frontend What is template engine? The Template Engine is used to merge HTML page with the data from your program. The engine is simple and powerful. At runtime, it replaces variables in a template file with actual values and transforms the template into an HTML file sent to the client. For Eg:- Welcome <%= username %> Here username is a variable.It will replace the username with the value received from the backend. Say username variable contains value  then the output will be:-...

Curl is a way you can hit a URL from your code to get an HTML response from it. In NodeJS/ExpressJS we use “request” module for this purpose. In Simple Words, if we want to access HTML content of any site we pass that URL to request( ) and it returns the HTML source code. By far out of all the modules 'Request' module is the most popular npm package to make HTTP request. Actually, it is really just a wrapper around Node's built-in HTTP module, so you can achieve all of the same functionality on your own with HTTP, but...

The middleware used for authentication in Node is Passport. It is designed to serve a singular purpose: authenticate requests. Normally users log in by providing a username and password. But today using an OAuth provider (such as Facebook or Twitter), it has become a popular authentication method. Here, we use Passport for local authentication with a MongoDB database. Topic Covered How to use Passport Authenticate Configure Example of Passport Install it by using npm: // Installing package locally $npm install passport Authenticate An authenticating request is made by calling passport.authenticate() function and specifying which strategy to use. app.post('/login', passport.authenticate('local'),// for...

Mongoose allows us to easily access MongoDB commands for CRUD. There is always a need to create, read, update, and delete information all the time. CRUD is the most necessary thing out there to do so. Topics Covered Initial steps to follow while working on mongoose Defining Schema and Model Inserting data into Database Query the Database Read Update Delete Initial steps to follow while working on mongoose Step 1: Be sure you have MongoDB and Node.js installed. Step 2: Install Mongoose from the command line. $ npm install mongoose --save Step 3: Include mongoose in our project. var mongoose = require('mongoose');...

ExpressJS use middleware pattern for the router handling. Express provides simple middleware which can be used to handle any run-time errors. In any case, if run-time errors happen in your app.js then, the app.js will not stop, rather it will call the error handling middleware. When we use express middleware we pass three parameters (req, res, next). If we use error handler middleware then we will pass one extra parameter, which is the error (error, req, res, next). Sample Code: var express = require('express'); var app = express(); var bodyParser = require('body-parser'); app.use(bodyParser); app.use(function (req, res, next) { console.log("In second route"); next();...

Request and Response object both are the callback function parameters and are used for Express.js and Node.js. You can get the request query, params, body, headers, and cookies. It can overwrite any value or anything there. However, overwriting headers or cookies will not affect the output back to the browser. Topics Covered Request object Request object properties Request object methods Response object Response object properties Response object methods Request object Express.js  is a  request & response objects parameters of the callback function and are used for the Express applications. The request object represents the HTTP request and contains properties for the...