Mern Technology Screening Test

By Collab Team Contributor / February 7, 2025

MERN Technology Screening Test

1 / 20

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

explain("executionStats")

find().stats()

profile()

queryPlanner()

2 / 20

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

Pauses the event loop

Executes a function in the next event loop iteration

Runs a function immediately

Delays function execution indefinitely

3 / 20

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

Using updateMany()

Using findAndModify()

Using bulkWrite()

Using a replica set and startSession()

4 / 20

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

HTTP headers

Route parameters from the URL

Request body

Query string parameters

5 / 20

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

It will throw an error

It will default to rendering an empty <div>

It will crash the application

It will render nothing

6 / 20

In React, why should we use keys in lists?

To manage event handlers efficiently

To improve performance by helping React identify changes

To style list elements dynamically

To store additional metadata

7 / 20

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

Using res.send(error.message)

Using process.exit()

Using throw new Error()

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

8 / 20

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

http

net

events

9 / 20

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

To handle dynamic data rendering

To define API routes

To serve static files such as images and CSS

To define middleware for error handling

10 / 20

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

http

path

stream

11 / 20

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

multer

cookie-parser

body-parser

express-validator

12 / 20

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

Routes can be defined using app.use()

Middleware runs after route handlers by default

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

Routes must always be defined in separate files

13 / 20

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

populate()

aggregate()

mapReduce()

lean()

14 / 20

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

Compound index

Geospatial index

Single-field index

Text index

15 / 20

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

To manage database transactions

To handle event-driven communication

To create and manage child processes for concurrency

To run multiple instances of Express.js

16 / 20

What is the purpose of useMemo() in React?

To perform side effects in functional components

To handle lifecycle methods

To manage component state

To memoize expensive calculations between renders

17 / 20

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

req and res only

req, res, and next

res and next only

req and next only

18 / 20

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

setState(newValue)

setState((prevState) => newValue)

setState({ ...prevState, newValue })

this.state = newValue

19 / 20

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

useState()

useReducer()

useContext()

useEffect()

20 / 20

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

$project

$match

$sort

$group

Your score is

The average score is 46%

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