DEV Community

Cover image for Crack your MERN interview with these questions
Unnati Bamania
Unnati Bamania

Posted on

Crack your MERN interview with these questions

MERN stack is one of the most powerful and in-demand web stacks in 2021. MERN is a free and open-source JavaScript software stack for building dynamic websites and web applications. MERN stack is basically based on JavaScript.

Here goes the list of top companies that use MERN stack for their development

Refer to this link

If you want to land up in some companies like these then you need to crack their interviews.
Hence, here goes the list of some important questions asked in the interview on the MERN stack.


  • What do you understand by NoSQL databases? Is MongoDB a NoSQL database? explain.
  • What is the difference between MongoDB and MySQL?
  • What is β€œNamespace” in MongoDB?
  • What is sharding in MongoDB?
  • How can you see the connection used by Mongos?
  • Does MongoDB support primary-key, foreign-key relationship?
  • If you remove an object attribute, is it deleted from the database?
  • In which format MongoDB represents document structure?
  • While creating Schema in MongoDB what are the points need to be taken into consideration?
  • Mention what is Objecld composed of?
  • Explain what is GridFS in MongoDB?
  • Does MongoDB provide a facility to do text searches? How?
  • What is a covered query in MongoDB?


  • How does Node.js work?
  • Explain callback in Node.js.
  • Why is Node.js Single-threaded?
  • What is NPM?
  • Explain the concept of middleware in Node.js.
  • What are the different types of HTTP requests?
  • Why is Node.js preferred over other backend technologies like Java and PHP?
  • What does event-driven programming mean?
  • What is an Event Loop in Node.js?
  • What are the two types of API functions in Node.js?
  • What are streams in Node.js?
  • What is the purpose of module.exports?
  • What is REPL in Node.js?
  • What is piping in Node.js?
  • What is the buffer class in Node.js?


  • What is React?
  • What is JSX?
  • What is the difference between Element and Component?
  • What are Pure Components?
  • When to use a Class Component over a Function Component?
  • What is the difference between state and props?
  • Why should we not update the state directly?
  • What is the difference between HTML and React event handling?
  • How to bind methods or event handlers in JSX callbacks?
  • What is the use of refs?
  • How to create refs?
  • What is Virtual DOM?
  • How Virtual DOM works?
  • What is the difference between Shadow DOM and Virtual DOM?
  • What is reconciliation?
  • What is context?
  • What are children prop?
  • What are fragments?
  • What is the purpose of getSnapshotBeforeUpdate() & lifecycle method?
  • What are React Mixins?
  • What is the difference between super() and super(props) in React using ES6 classes?

Credits and References

One has to be strong with basics and understand the concepts properly. Some amount of preparation and research will do. If you like to add on some resources or questions please do mention them in the comment section below.

Top comments (5)

hkara107144 profile image

Hi,is there any resource to learn mern stack you advice ?

amirshojay profile image

Based on my experience, " " provides the best and easy-to-learn tutorials.
Here are some courses that can help you become a mern stack developer.

Nodejs, Express, MongoDB :

Each course costs $11.99
There are of course free tutorials out there, but if you afford it, I believe these are the best sources you can find on the internet. :)

commentme profile image
Unnati Bamania


andrewbaisden profile image
Andrew Baisden

Agreed Udemy has lots of great courses.

commentme profile image
Unnati Bamania

Hi, there are a lot of resources available for learning MERN stack
Nodejs and MongoDb
Udemy course by maxmilian
Udemy course by Stephen Grider
Course By Angela Yu

React JS
Course by Maximilian
Course by Stephen Grider
Course by Brad Traverse

Once you're done of with any one of the courses and confident enough then go for building code along projects. Brad Travesy has a some good projects for MERN stack web development