Express.js is a minimal and flexible Node.js web application framework that provides a robust set of features for web and mobile applications. Express provides a thin layer of fundamental web application features, without obscuring Node.js features that you know and love.Node.js is a platform for building the i/o applications which are server-side event-driven and made using JavaScript.Express.js is a framework based on Node.js for which is used for building web-application using approaches and principles of Node.js.event-driven.| Feature | Express.js | Node.js |
|---|---|---|
| Usage | It is used to build web-apps using approaches and principles of Node.js. | It is used to build server-side, input-output, event-driven apps. |
| Level of features | More features than Node.js. | Fewer features. |
| Building Block | It is built on Node.js. | It is built on Google’s V8 engine. |
| Written in | JavaScript | C, C++, JavaScript |
| Framework/Platform | Framework based on Node.js. | Run-time platform or environment designed for server-side execution of JavaScript. |
| Controllers | Controllers are provided. | Controllers are not provided. |
| Routing | Routing is provided. | Routing is not provided. |
| Middleware | Uses middleware for the arrangement of functions systematically server-side. | Doesn’t use such a provision. |
| Coding time | It requires less coding time. | It requires more coding time. |
Node.js, create a directory to hold your application, and make that your working directory.$ mkdir myapp
$ cd myapppackage.json file for your application. For more information on how package.json works, see Specifics of npm’s package.json handling.$ npm initentry point: (index.js)app.js, or whatever you want the name of the main file to be. If you want it to be index.js, hit RETURN to accept the suggested default file name.$ npm install express$ npm install express --no-saveExpress.js is an automatically prebuilt Node.js framework that facilitates us to create server-side web applications faster and smarter. The main reason for choosing Express is its simplicity, minimalism, flexibility, and scalability characteristics. npm install –g yeomanprocess.ENV :.env” is to be created within the project folder..env” file.server.js.require.JS :config.json” is to be created within the config folder within the project folder.config.json file.config.json file.Resourceful routingNode.js web application framework, it provides a robust set of features for web and mobile applications. Following is the list of some distinctive features of this framework :.js" extension.var express = require('express');
var app = express();
app.get('/', function (req, res) {
res.send('Welcome to Free Time Learning!');
});
var server = app.listen(8000, function () {
var host = server.address().address;
var port = server.address().port;
console.log('Example app listening at http://%s:%s', host, port);
}); ​Node.js command prompt, the app will listen at the specified server address and give the following output.Welcome to Free Time Learning!var bodyParser = require('body-parser')
app.use( bodyParser.json() ); // to support JSON-encoded
app.use(bodyParser.urlencoded({ // to support URL-encoded
extended: true
})); Express.js, add the subsequent code in server.js :app.all('*', function(req, res, next) {
res.set('Access-Control-Allow-Origin', '*');
res.set('Access-Control-Allow-Methods', 'GET, POST, DELETE, PUT');
res.set('Access-Control-Allow-Headers', 'X-Requested-With, Content-Type');
if ('OPTIONS' == req.method) return res.send(200);
next();
});$ DEBUG=express:* node index.jsset DEBUG=express:* & node index.jsC:\Program Files (x86)\JetBrains\WebStorm 2016.2.4\bin\runnerw.exe"
"C:\Program Files\nodejs\node.exe" --debug-brk=61081 --expose_debug_as=v8debug
E:\Development\nodejd\librarey\bin\wwwExpress.js version 4 and above, we have to install a middleware module called body-parser. Body-parser extracts the entire body portion of an incoming request stream and exposes it on req. body, The Middleware was a part of Express.js earlier, but now you have to install it separately. You can install it by using the following command :npm install MODULE_NAME var bodyParser = require('body-parser');
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }))
Note: You can use multiple middleware as an array on a single route.var middlewareArray = [middleware1, middleware2]
app.get('/home', middlewareArray, function (req, res, next) {
//Code snippets
}) npm install express-generator -g
express myApp myApp" will be created along with following the files/folders in the project.cd myApp
npm installnpm install -g yeoman | Aspects | Express.js | Django |
|---|---|---|
| Architecture | Express follows the MVC architecture. | Django supports the MTV (Model Template View) design. It uses managing data for interacting and validating. |
| Framework | Express is a free, open-source, lightweight, and fast backend web application framework for Node.js to build single-page, multi-page, and hybrid web applications and APIs. | This is a Python-based framework used to develop computer apps in a specified time frame. |
| Efficiency | It is best for developing web applications rapidly on Node.js. | It is more efficient and delivers at a fast speed so, it is cost-effective. |
| Programming language | The Express framework is programmed in Node.js. | Django is programmed in Python programming language. |
| Complexity | Express.js is less complex than Django. | Django is more complex than Express.js |
| Scalability | It provides better scalability. | It is less scalable. |
| Flexibility | Express is a flexible, minimal API-developing Node.js tool. | It provides limited flexibility. |
| Full-stack development | It provides a full-stack development that reduces the cost as you don't need to hire several developers to administer a web application's backend and frontend. | It does not deliver full-stack development. |
| Companies using this technology | Companies such as PayPal, IBM, Fox Sports, etc., are using this technology. | Companies such as Instagram, Mozilla, Bitbucket, etc., are using this technology. |
// error handler
app.use(function(err, req, res, next) {
// set locals, only providing error in development
res.locals.message = err.message;
res.locals.error = req.app.get('env') === 'development' ? err : {};
// render the error page
res.status(err.status || 500);
res.render('error');
}); ​npm install errorhandler --save var errorhandler = require('errorhandler') if (process.env.NODE_ENV === 'development') {
// only use in development
app.use(errorhandler({log: errorNotification}))
}
function errorNotification(err, str, req) {
var title = 'Error in ' + req.method + ' ' + req.url
notifier.notify({
title: title,
message: str
})
} app.use(express.static('public'))
app.use('/static', express.static(path.join(__dirname, 'public'))) npm install pugconst express = require ('express')
const app = express()
app.set ('view engine', 'pug')app.get('/user details/:id?', function(req, res, next));server.js add the subsequent code to send 404 errors back to a page in our ExpressJS App :/* Define fallback route */
app.use(function(req, res, next) {
res.status(404).json({errorCode: 404, errorMsg: "route not found"});
});app.use() method. It applies on all routes.//This middleware will execute for each route.
app.use(function (req, res, next) {
console.log('Current Time:', Date.now())
next()
}) express.Router().Built-in Middleware : The built-in Middleware was introduced with version 4.x. It ends the dependency on Connect.Express.js :eventEmitter.on(). | Type | Value |
|---|---|
| Boolean |
If If |
| IP addresses |
An IP address, subnet, or an array of IP addresses and subnets to trust as being a reverse proxy. The following list shows the pre-configured subnet names:
You can set IP addresses in any of the following ways: When specified, the IP addresses or the subnets are excluded from the address determination process, and the untrusted IP address nearest to the application server is determined as the client’s IP address. This works by checking if |
| Number |
Use the address that is at most |
| Function |
Custom trust implementation. |
req.hostname is derived from the value set in the X-Forwarded-Host header, which can be set by the client or by the proxy. req.protocol. req.ip and req.ips values are populated based on the socket address and X-Forwarded-For header, starting at the first untrusted address. Express 5.0 is still in the beta release stage, but here is a preview of the changes that will be in the release and how to migrate your Express 4 app to Express 5.$ npm install "express@>=5.0.0-beta.1" --save