Collab Team Contributor - VOE Cosmopolitan PVT LTD

MERN Technology Screening Test

1 / 20

In MongoDB, which aggregation stage is used to reshape documents, adding or removing fields?

$sort

$match

$project

$group

2 / 20

What is the purpose of the cluster module in Node.js?

To create and manage child processes for concurrency

To manage database transactions

To run multiple instances of Express.js

To handle event-driven communication

3 / 20

How do you update state based on the previous state in React?

setState({ ...prevState, newValue })

this.state = newValue

setState((prevState) => newValue)

setState(newValue)

4 / 20

Which hook is used to handle side effects in functional components?

useState()

useEffect()

useContext()

useReducer()

5 / 20

Which MongoDB index type is best suited for queries involving text search?

Text index

Geospatial index

Compound index

Single-field index

6 / 20

What does process.nextTick() do in Node.js?

Runs a function immediately

Pauses the event loop

Executes a function in the next event loop iteration

Delays function execution indefinitely

7 / 20

Which of the following is a recommended way to perform transactions in MongoDB?

Using findAndModify()

Using updateMany()

Using a replica set and startSession()

Using bulkWrite()

8 / 20

Which middleware is commonly used to parse JSON request bodies in Express.js?

multer

body-parser

express-validator

cookie-parser

9 / 20

What will happen if a function component in React returns null?

It will render nothing

It will crash the application

It will throw an error

It will default to rendering an empty <div>

10 / 20

Which built-in Node.js module is used to create an HTTP server?

http

events

net

fs

11 / 20

What does req.params contain in an Express route handler?

Route parameters from the URL

HTTP headers

Request body

Query string parameters

12 / 20

Which command provides a detailed execution plan of a MongoDB query?

queryPlanner()

profile()

explain("executionStats")

find().stats()

13 / 20

In React, why should we use keys in lists?

To store additional metadata

To style list elements dynamically

To improve performance by helping React identify changes

To manage event handlers efficiently

14 / 20

Which of the following methods in Mongoose is used to populate referenced documents?

populate()

mapReduce()

lean()

aggregate()

15 / 20

What is the purpose of useMemo() in React?

To perform side effects in functional components

To memoize expensive calculations between renders

To handle lifecycle methods

To manage component state

16 / 20

Which of the following statements is true about Express.js routing?

Middleware runs after route handlers by default

Routes can be defined using app.use()

Routes support HTTP methods like GET, POST, PUT, DELETE

Routes must always be defined in separate files

17 / 20

Which Node.js module is used to work with file systems?

stream

path

fs

http

18 / 20

How do you handle errors globally in an Express.js application?

Using throw new Error()

Using process.exit()

Using res.send(error.message)

Using a middleware with (err, req, res, next) signature

19 / 20

What is the primary purpose of using express.static()?

To handle dynamic data rendering

To serve static files such as images and CSS

To define middleware for error handling

To define API routes

20 / 20

In Express.js, middleware functions have access to which of the following objects?

req and next only

req, res, and next

req and res only

res and next only

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