Interview Questions.

ExpressJs Interview Questions and Answers

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ExpressJs Interview Questions and Answers

Q1. What is Express.Js?

Ans: Express.Js is a light-weight node.Js based totally web utility framework. This JavaScript framework affords a number of flexible and beneficial feature so that it will broaden cellular as well as net utility the use of NodeJS.

Q2. How to install explicit js in node?

Ans: Use following command to install express js. :

npm installation express

Q3. What sort of web utility can built using Express JS?

Ans: You can construct unmarried-page, multi-web page, and hybrid net packages.

Q4. Why to use Express?

Ans: You have to use Express because provides following capabilities:

Parses the arguments and headers

Supports Routing

Supports a couple of view engines like Jade, EJS, JSHtml etc.

Handle Configurations.

Supports Sessions

Supports Content Negotiation

Supports Error Handling

Supports Multiple Databases:

o RDBMS – MySQL, MS SQL and so on.

O NoSQL – MongoDB, Firebase, Redis etc.

Q5. List out the ExpressJS Features.

Ans: Following are some of the core features of Express framework:

Set up middlewares with the intention to reply to HTTP/RESTful Requests.

It is viable to defines a routing desk with a purpose to perform distinct HTTP operations.

Dynamically renders HTML Pages based on passing arguments to templates.

Provides all the characteristic presents by middle Node.Js.

Express prepare a thin layer, consequently, the performance is good enough.

Organize the web application into an MVC structure.

Manages the whole thing from routes to rendering view and preforming HTTP request.

Q6. How to create an Http server the use of Express?

Ans: Express is great for growing net application using Node.Js. You can create an http server the usage of explicit as given under:

var specific = require("specific" );

var app = specific();

app.Get( "/", characteristic (req, res) 

res.Write("Hello, Express");

res.Give up();

);

var port = process 1305;

app.Concentrate(port);

console.Log("Server is walking at http://localhost:" + port);

Q7. How To Install Expressjs?

Ans: Assuming you’ve already installed Node.Js, create a directory to hold your utility, and make that your running listing.

$ mkdir myapp

$ cd myapp

Use the npm init command to create a bundle.Json report for your software. For more records on how package deal.Json works, see Specifics of npm’s package deal.Json handling.

$ npm init

This command activates you for a number of of factors, consisting of the call and version of your application. For now, you could genuinely hit RETURN to simply accept the defaults for maximum of them, with the subsequent exception:

entry factor: (index.Js)

Enter app.Js, or whatever you want the name of the primary file to be. If you want it to be index.Js, hit RETURN to just accept the suggested default record name.

Now set up Express within the myapp directory and shop it inside the dependencies list. For example:

$ npm installation explicit --shop

To deploy Express quickly and not upload it to the dependencies list, leave out the --shop option:

$ npm set up express

Q8. What are exceptional strategies in REST API?

Ans: GET : Used to study.

POST: Used to replace.

PUT: Used to create.

DELETE: Used to delete.

Q9. How to use explicit js in node?

Ans: Use require to include explicit module.

Var app = require('specific')();

Q10. How to apply take care of get request in explicit.Js?

Ans: /*Include require module*/

var app = require('express')();

var http = require('http').Server(app);

app.Get('/', function (req, res) 

console.Log("Got a GET request for the homepage");

//Shown in console res.Ship('This is GET Method for Homepage'); //

Display as reaction

)

/*Start listing 8080 port*/

http.Listen('8080', characteristic() 

console.Log('listening on *:8080');

);

Q11. What Function Arguments Are Available To Express.Js Route Handlers?

Ans: The arguments to be had to an Express.Js course handler characteristic are:

req: the request item

res: the reaction item

subsequent (elective): a feature to bypass manipulate to one of the subsequent route handlers.

The 0.33 argument may be neglected, but is beneficial in cases wherein you have got a series of handlers and also you would love to pass manipulate to one of the next route handlers, and bypass the contemporary one.

Q12. What is template engine?

Ans: A template engine permits us to create and render an HTML template with minimal code. At runtime, a template engine executes expressions and replaces variables with their real values in a template report. In this manner, it transforms the template into an HTML record and sent to it the customer.

Q13. What template engines you may use with express?

Ans: The famous template engines which you may use with Express are Pug, Handlebars, Mustache, and EJS. The Express utility generator uses Pug as its default template engine.

Q14. How to download a document?

Ans: app.Get('/down load', function(req, res)

var report = __dirname + '/download-folder/document.Txt';

res.Down load(record);

);

Q15. How to get variables in Express.Js in GET Method? 

Ans: var express = require('express');

var app = express();

app.Get('/', characteristic(req, res)

/* req have all the values **/

res.Ship('identification: ' + req.Question.Identification);

);

app.Pay attention(3000);

Q16. How to get POST a question in Express.Js?

Ans: var bodyParser = require('frame-parser') app.Use( bodyParser.Json() );

// to help JSON-encoded

app.Use(bodyParser.Urlencoded(

// to help URL-encoded

prolonged: genuine

));

Q17. What is the parameter “next” used for in Express? 

Ans: app.Get('/userdetails/:id?', characteristic(req, res, next) );

req and res which constitute the request and response items

nextIt passes manage to the following matching route.

Q18. What is frame-parser?

Ans: Parse incoming request our bodies in a middleware before your handlers, to be had below the req.Body belongings.

To manage HTTP POST request in Express.Js version four and above, you want to put in middleware module known as frame-parser.

Frame-parser extract the entire body portion of an incoming request circulation and exposes it on req.Frame.

Installation

$ npm installation frame-parser

API

var bodyParser = require('frame-parser')

Example

var specific = require('specific')

var bodyParser = require('body-parser')

var app = express()

// parse application/x-www-form-urlencoded

app.Use(bodyParser.Urlencoded( extended: false ))

// parse utility/json

app.Use(bodyParser.Json())

app.Use(characteristic (req, res) 

res.SetHeader('Content-Type', 'textual content/undeniable')

res.Write('you published:n')

res.Stop(JSON.Stringify(req.Frame, null, 2))

)




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