Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
-
Economics & Finance
Articles on Trending Technologies
Technical articles with clear explanations and examples
Express.js – express.json() function
express.json() is a built-in middleware function in Express. This method is used to parse the incoming requests with JSON payloads and is based upon the bodyparser.This method returns the middleware that only parses JSON and only looks at the requests where the content-type header matches the type option.Syntaxexpress.json([options])ParametersFollowing are the different options available with this methodoptionsinflate – This enables or disables the handling of the deflated or compressed bodies. Default: truelimit – This controls the maximum size of the request body.reviver – This option is passed to the JSON.parse method as the second argument.strict – This enables or disables the ...
Read MoreExpress.js – app.set() Method
The app.set() function assigns or sets a setting name to value. This can store any type of value as the user wants, but there are some certain names that can be used to configure the behaviour of the serverSome of the properties that can be configured with the set functionality are −envetagjsonp escape, etcSyntaxapp.set(name, value)Example 1Create a file with the name "appSet.js" and copy the following code snippet. After creating the file, use the command "node appSet.js" to run this code.// app.set() Demo Example // Importing the express module var express = require('express'); // Initializing the express and ...
Read MoreExpress.js – app.route() Method
The app.route() method returns the instance of a single route. This single route can be used to handle the HTTP verbs with the optional middleware. This method is mainly used to avoid duplicate names.Syntaxapp.route( )Example 1Create a file with the name "appRoute.js" and copy the following code snippet. After creating the file, use the command "node appRoute.js" to run this code.// app.route() Demo Example // Importing the express module var express = require('express'); // Initializing the express and port number var app = express(); var PORT = 3000; // Creating a get, post & other requests app.route('/user') ...
Read MoreExpress.js – app.post() Method
The app.post() method routes all the HTTP POST requests to the specified path with the specified callback functions.Syntaxapp.path(path, callback, [callback])Parameterspath − This is the path for which the middleware function is invoked. A path can be a string, path pattern, a regular expression or an array of all these.callback − These are the middleware functions or a series of middleware functions that acts like a middleware except that these callbacks can invoke next (route).Example 1Create a file with the name "appPost.js" and copy the following code snippet. After creating the file, use the command "node appPost.js" to run this code.// ...
Read MoreExpress.js – app.path() Method
The app.path() method returns the canonical path. The path is returned as a string. It is better to use the req.baseUrl method since the app.path() method can be very complicated in complex cases of mounted apps.Syntaxapp.path( )Example 1Create a file with the name "appPath.js" and copy the following code snippet. After creating the file, use the command "node appPath.js" to run this code.// app.path() Demo Example // Importing the express module var express = require('express'); // Initializing the express and port number var app = express(); var PORT = 3000; // Assigning express constructor var app = ...
Read MoreExpress.js – app.param() Method
The app.param() method is basically used for adding the callback triggers to the route parameters, where name represents the name of the parameter or an array of them and callback represents the callback function.Syntaxapp.param([name], callback)Parametersname − Represents the name of the parameter or array of parameters as required.callback − Represents the callback function. The parameters of the callback function include the request object, the response object, the next middleware, the value of the parameter, and the name of the parameter in the same order.ExampleCreate a file with the name "appParam.js" and copy the following code snippet. After creating the file, ...
Read MoreExpress.js – app.mountpath Property
The app.mountpath property contains those path patterns on which a sub-app was mounted. A sub-app can be defined as an instance of Express that may be used for handling the request to a route.This property is similar to the baseUrl property of the req object; the only difference is that req.baseUrl returns the matched URL path instead of the matched patterns.Syntaxapp.mountpathExample 1Create a file "appMountpath.js" and copy the following code snippet. After creating the file, use the command "node appMountpath" to run this code.// app.mountpath code Demo Example // Importing the express module var express = require('express'); // ...
Read MoreExpress.js – app.locals Property
The app.locals object defines the properties that are local variables inside an application. Once the value of app.locals property is set, it persists throughout the life of the application. The res.locals property is valid only for the lifetime of the request.Syntaxapp.localsExample 1Create a file "appLocals.js" and copy the following code snippet. After creating the file, use the command "node appLocals.js" to run this code.// app.locals code Demo Example // Importing the express module var express = require('express'); // Initializing the express and port number var app = express(); // Setting the below email throught out the application ...
Read MoreExpress.js – app.listen() Method
The app.listen() method binds itself with the specified host and port to bind and listen for any connections. If the port is not defined or 0, an arbitrary unused port will be assigned by the operating system that is mainly used for automated tasks like testing, etc.The app object returned by express() is a JavaScript function, that is passed to Node’s HTTP servers as a callback which handles the requests. This makes the application to provide both HTTP and HTTPS versions of the same app with the same code base, as the app does not inherit from these.Syntaxapp.listen([port], [host], [backlog], ...
Read MoreExpress.js – app.engine() Method
The app.engine() method is used for registering the given template engine callback as "ext". The require() method needs the engine based on the function by default.Use the following methods for engines that do not provide the extensions (or want to map different extensions) or express out of the box.app.engine('html', require('ejs').renderFile)Syntaxapp.engine(ext, callback)Example 1Create a file with the name "appEngine.js" and copy the following code snippet. After creating the file, use the command "node appEngine.js" to run this code.// app.engine() Method Demo Example // Importing the express module const express = require('express'); // Initializing the express and port number var ...
Read More