ExpressJS

                  - Is a web application framework for Nodejs

                  - Discharged as free and open source computer program                              under the MIT Permit

                  - Is outlined for building web applications and APIs

                  - Provides a robust set of features for web and mobile                                     applications

                  - Developed ans maintained by the Node js foundation

                  - High performance, extensible and reusable 

How to start developing and using the Express Framework.

• You should have the Node and the npm (node package manager) installed.

• Confirm that node and npm are installed by running the following commands in terminal.

                          node --version
                          npm -- version

• Start your terminal/cmd, create a new folder

• Now to create the package.json file using npm

                           npm init

• To install Express and add it to our package.json file, use the following command

                          npm install --save express

• To make our development process a lot easier, we will install a tool from npm, nodemon. This tool restarts our server as soon as we make a change in any of our files

             npm install -g nodemon

Simple project using Express js

Print Hello world using Expressjs

var express = require('express');

var app = express();

app.get('/', function(req, res){

   res.send("Hello world!");

});

app.listen(3000);

Save the file, go to your terminal and type the following.

nodemon index.js

ExpressJS – Best Practices :

• Always begin a node project using npm init.

• Always install dependencies with a –save or –save-dev. This will ensure that if you move to a different platform, you can just run npm install to install all dependencies.

• Stick with lowercase file names and camelCase variables. If you look at any npm module, its named in lowercase and separated with dashes. Whenever you require these modules, use camelCase.

• Don’t push node_modules to your repositories. Instead npm installs everything on development machines.

• Use a config file to store variables

• Group and isolate routes to their own file. For example, take the CRUD operations in the movies example we saw in the REST API page.