MERN Stack Developer Interview Questions And Answers For Freshers

MERN Stack Developer Interview Questions And Answers For Freshers

Dec 27, 2022·

4 min read

Mern stack is one of the most emerging technologies in the Information Technology Sector, The need for Mern developers in the market is huge in India, Average salary of a MERN Stack developer in India is 5 Lakhs Per Annum and In this article, we will go through some of the important Mern Stack Developer Interview Questions And Answers For Freshers.

1. Why do you get a Router that may have only one child element warning?

You have to wrap your Router in a <Switch> block because <Switch> is unique in that it renders a route.

Initially wanna add Switch to the imports:

import { Switch, Router, Route } from 'react-router'

And, then define the routes within <Switch> block:



&lt;Route {/\* ... \*/} /&gt;

&lt;Route {/\* ... \*/} /&gt;



2. What is replication in MongoDB?

Replication synchronizes the data across multiple servers. Replication helps to increase the data availability and redundancy along with different servers and multiple copies. It also allows us to recover from hardware failure and interruptions in services.

3. What is React Fiber? Goal of React Fiber?

React Fiber is a reimplementation of the core algorithm in React Version 16. The main purpose of React Fiber is to increase the usability of the features like animation, layout, pause, play, abort, or reuse work and many other features and it can split rendering tasks into chunks and split them over into multiple frames.

4. What is Callback Hell?

The asynchronous function requires a callback as a return parameter where multiple asynchronous functions are chained together then the callback hell comes into action.

5. What is aggregation in MongoDB?

It returns group from multiple documents and returns computed results, It takes over the various document data and runs some operations on it which is designed by the developers, After the completion of the operations it returns the computed results, And aggregation has three types of ways to perform aggregation they are :

  • Aggregate pipeline

  • Map reduce function

  • Single-purpose aggregation methods

6. Disadvantages of using ReactJs?

React has some limitations such as writing code being complicated as it uses jsx and inline template formatting, React is a simple library, not a complete framework so it calls for dependencies.

7. Phases of Component lifecycle in React?

React component lifecycle runs around three phases

Initial rendering: In this phase, it involves the beginning of the journey of the react component to the document object model.

Update: In the update, the component can be updated and rendered again and again if required after it gets added to the Document object model

Unmounting: The final phase of react component lifecycle is Unmounting, which involves the destruction of the component and its eventual removal from the Document Object Model.

8. Differentiate between a controlled component and an uncontrolled component in ReactJs?

In a controlled component React Js will have complete control over the component and it is the singular point of data for the forms, In an Uncontrolled component where the form data gets handled by the document Object Model but not by the react component and is usually done using refs in React.

9. What are hooks in React?

Hooks are used to making use of the state and other features without having an explicit need to write a class and extract logic from a component so that it can be tested independently and can be reused and it allows you to reuse logic without changing your component hierarchy.

10. What are Refs in React?

Reference in react is called Ref, Ref is used to storing a reference to a single react element and lately, it has been named a render function main use of it is to join third-party dom libraries and to manage focus and media playback.

Conclusion :

The above-mentioned are the most important Mern Stack Interview questions and answers for freshers. Having a skill in Mernstak development by learning them in a structured way with hands-on experience will help you to land a high-paying Job.

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