Mern Technology Screening Test

By Collab Team Contributor / February 7, 2025

MERN Technology Screening Test

1 / 20

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

To define middleware for error handling

To serve static files such as images and CSS

To handle dynamic data rendering

To define API routes

2 / 20

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

res and next only

req and next only

req and res only

req, res, and next

3 / 20

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

net

events

http

4 / 20

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

Request body

Query string parameters

Route parameters from the URL

HTTP headers

5 / 20

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

find().stats()

queryPlanner()

explain("executionStats")

profile()

6 / 20

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

Using updateMany()

Using bulkWrite()

Using a replica set and startSession()

Using findAndModify()

7 / 20

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

Executes a function in the next event loop iteration

Runs a function immediately

Pauses the event loop

Delays function execution indefinitely

8 / 20

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

multer

cookie-parser

express-validator

body-parser

9 / 20

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

Using throw new Error()

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

Using res.send(error.message)

Using process.exit()

10 / 20

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

$project

$match

$group

$sort

11 / 20

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

aggregate()

lean()

mapReduce()

populate()

12 / 20

What is the purpose of useMemo() in React?

To perform side effects in functional components

To manage component state

To memoize expensive calculations between renders

To handle lifecycle methods

13 / 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

14 / 20

In React, why should we use keys in lists?

To store additional metadata

To manage event handlers efficiently

To improve performance by helping React identify changes

To style list elements dynamically

15 / 20

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

To handle event-driven communication

To create and manage child processes for concurrency

To manage database transactions

To run multiple instances of Express.js

16 / 20

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

Compound index

Text index

Geospatial index

Single-field index

17 / 20

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

setState(newValue)

this.state = newValue

setState((prevState) => newValue)

setState({ ...prevState, newValue })

18 / 20

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

useEffect()

useContext()

useReducer()

useState()

19 / 20

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

It will crash the application

It will default to rendering an empty <div>

It will throw an error

It will render nothing

20 / 20

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

http

stream

path

Your score is

The average score is 46%

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