Found 72 Articles for Express JS

We need to get the DNS information to track the address from where we receive the requests. This feature also provides an added layer of security, protecting the application from different type of DOS and DDOS attacks.We can use the following functions to get the domain and host information.SyntaxGetting the origin info:var origin = req.get('origin');Getting the host info:var host = req.get('host');Example 1Create a file with the name "dnsInfo.js" and copy the following code snippet. After creating the file, use the command "node dnsInfo.js" to run this code as shown in the example below −// Getting the Host info Demo Example ... Read More

In Express.js, you can directly use the req.query() method to access the string variables. As per the documentation, the req.param method only gets the route parameters, whereas the req.query method checks the query string parameters. For example, "?id=12" checks urlencoded body params.Syntaxreq.query( )Example 1Create a file with the name "reqQuery.js" and copy the following code snippet. After creating the file, use the command "node reqQuery.js" to run this code as shown in the example below −// req.query() Demo Example // Importing the express module var express = require('express'); // Initializing the express and port number var app = express(); ... Read More

The req.acceptsLanguage() method returns the first accepted language out of the specified languages based on the request's Accept-Language HTTP header field. This method returns 'false' if none of the specified language is accepted.Syntaxreq.acceptsLanguage ( lang, [...] )Example 1Create a file with the name "reqLang.js" and copy the following code snippet. After creating the file, use the command "node reqLang.js" to run this code as shown in the example below −// req.acceptsLanguage(lang, [...]) Method Demo Example // Importing the express module var express = require('express'); // Initializing the express and port number var app = express(); // Initializing the ... Read More

The req.acceptsCharsets() method returns the first accepted charset of the specified charset sets. These charsets are based on the request's Accept-Charset HTTP header field. By default, it returns 'false' if none of the specified charsets is accepted.Syntaxreq.acceptsCharsets ( charset, [...] )Example 1Create a file with the name "reqAcceptsCharsets.js" and copy the following code snippet. After creating the file, use the command "node reqAcceptsCharsets.js" to run this code as shown in the example below −// res.acceptsCharsets(lang, [...]) Method Demo Example // Importing the express module var express = require('express'); // Initializing the express and port number var app = express(); ... Read More

The req.accepts() method checks if the specified content-types are acceptable by the request's Accept HTTP header fields. This method returns the best match, and returns False if none of the specified content types is acceptable.The type values can be a MIME type like application/json, or an extension name like json.Syntaxreq.accepts( types )Example 1Create a file with the name "reqAccepts.js" and copy the following code snippet. After creating the file, use the command "node reqAccepts.js" to run this code as shown in the example below −// req.accepts() Method Demo Example // Importing the express module var express = require('express'); // ... Read More

express.urlencoded() is a built-in middleware in Express.js. The main objective of this method is to parse the incoming request with urlencoded payloads and is based upon the body-parser.This method returns the middleware that parses all the urlencoded bodies.Syntaxexpress.urlencoded( [options] )ParametersFollowing are the different options available with this method −options −inflate − This enables or disables the handling of the deflated or compressed bodies. Default: truelimit − This controls the maximum size of the request body.extended − This option allows to choose between parsing the URL encoded data with the queryString Library or the qs Library.type − This determines the media ... Read More

We can send different HTTP status and responses over the Express.js app endpoint as per the user's requirement. Also we can send a message in case of an error or when the requests are forbidden. The status code 200 is sent by default with the response returned.Syntaxres.status( statusCode )Example 1Create a file with the name "status.js" and copy the following code snippet. After creating the file, use the command "node status.js" to run this code as shown in the example below −// Specifying status code Demo Example // Importing the express module var express = require('express'); // Initializing ... Read More

You need to pass some parameters to skip the middleware in an Express application. On the basis of that parameter with logic in place, you can decide whether to execute a middleware or notSyntaxThere is no syntax defined. You can introduce a parameter and then check based upon that parameter whether to use the middleware or not.ExampleCreate a file with the name "skipMiddleware.js" and copy the following code snippet. After creating the file, use the command "node skipMiddleware.js" to run this code as shown in the example below −// app.set() Demo Example // Importing the express module var express ... Read More

res.headersSent returns a Boolean value that indicates if the app has sent HTTP headers for the response or not. If the headers are sent, it returns True; else False.Syntaxres.headersSentExample 1Create a file with the name "headersSent.js" and copy the following code snippet. After creating the file, use the command "node headersSent.js" to run this code as shown in the example below −// res.headersSent Property Demo Example // Importing the express module var express = require('express'); // Initializing the express and port number var app = express(); // Initializing the router from express var router = express.Router(); var ... Read More

router.param(name, callback) adds a callback to the route parameters where name defines the name of the parameter and callback is the callback function.Following are the parameters of the callback function −req – the request objectres – the response objectnext -- the next middlewarename – value of the name parameterSyntaxrouter.param( name, callback )ExampleCreate a file with the name "routerParam.js" and copy the following code snippet. After creating the file, use the command "node routerParam.js" to run this code as shown in the example below −// router.param() Method Demo Example // Importing the express module var express = require('express'); // Importing ... Read More