Skip to main content

What is ExpressJS





Express is a very popular framework that is used in NodeJs. Express is build upon NodeJs and also it provides a lot of tools that makes node more easy to use by adding more functionalities. Most of the needed functionalities are handled by express which helps the users to only focus on the business logic and to easily setup routes and to render the things on screen in a fast, optimized and a secured manner.


How to install ExpressJS?

Express can be easily installed by the command  "npm i express" .


Installation of ExpressJs

package.json file will be updated once the installation is successful.


How to import ExpressJS?

To import the installed express module we can use the command " require("express") " .



Accessing the imported express module.

express can be accessed as given below using the given commands.

Firstly a constant called app is created.


And then using this give constant app we can run server as well as we can include the middle wares that are needed by the application.


Port that the server should run is 4000 .

Running the server in port 4000

  
Using middle wares with the help of  express .


Creating routers using ExpressJS.

Routers can be created using ExpressJs by using the command  "express.Router()" .






Labels

Labels:

Comments

Post a Comment

Popular posts from this blog

Basic concepts on NodeJs

Usecases of NodeJS. Walmart and ebay. Node is not the best platform for CPU intensive heavy computational applications. But it is ideal for building fast and scalable network applications.  NodeJS is capable of handling a huge number of simultaneous connections with high throughput. For each connection NodeJS does not spawn new Thread causing max out of memory instead handle all in single thread using non-blocking I/O model. Using this architecture NodeJS has achieved over 1 Million concurrent connections. Bubbling errors up to NodeJS core event loop will cause crashing the entire program. Netflix and Uber. NodeJs is best for, I/O bound applications. Data streaming applications. Data intensive real-time applications. JSON APIs based applications. Single page applications. Modules in NodeJS. In order  a design to be reliable and maintainable should avoid defining variables and functions in the global scope. Instead we can use modular...
Post a Comment
Read more

RESTful API

Routers can be created according to REST principles such as get, post, put, delete etc..  GET  =>  get request to r etrieve data from database or data store(An array). POST  =>  post request to insert   data to database or data store(An array). PUT  =>  put request to update the data in database or data store(An array). DELETE  =>  delete request to delete data in database or data store(An array). Creation of routers. In this scenario I have created a schema call users using mongoose.  using mongoose the created users model is retrieved. GET request  using the keyword  " get"   the data can be retrieved.  retrieving all the users in the database. By giving a parameter in the url we can get information according to the given subject.  user is retrieved according to the _id. POST request  using the keyword  "pos t"   the...
Post a Comment
Read more

Callbacks,Promises,Async Await and Closure in JavaScript.

This weeks blog will be including about callbacks and issues of it,promises which was used to overcome the issues of callbacks and closure in JavaScript. Callbacks, promises and async await All theses ways are used to deal with asynchronous data. By default, JavaScript programs run using a single thread. Though there are ways to create new threads, JavaScript is considered as single threaded language. JavaScript does not wait for I/O operations to get completed, instead it continues the execution of the program. This is called as non-blocking I/O. So that JavaScript is an asynchronous programming language because of this NIO nature. Callbacks, Promises and Async Await. As an example when a request is made to a server it will take couple of seconds to response with the relevant data, therefore you do not want to stall your program till the data is returned. You must keep on going or doing something where callbacks come in. Extra facts. until es6 => callbacks were used es...
Post a Comment
Read more