VELOTIO Technologies React Js Frontend Developer Interview Questions and Answers

Focused on JS questions

Q1. React concept explain
Ans. 
React is a JavaScript library for building user interfaces.
• React is a declarative, efficient, and flexible JavaScript library for building user interfaces.

• It allows developers to create reusable UI components.

• React uses a virtual DOM to improve performance by only updating the necessary parts of the actual DOM.

• React follows a unidirectional data flow, making it easier to understand how data changes over time.

• React can ...read more
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Decent questions asked in the online mcq test

Q1. Redux vs context API
Ans. 
Redux is a predictable state container for JavaScript apps, while Context API is a feature in React for passing data through the component tree.
• Redux is more suitable for larger applications with complex state management needs.

• Context API is simpler to use and is built into React, reducing the need for additional libraries.

• Redux provides a single source of truth for the application state, making it easier to debug and ...read more
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Round duration - 60 minutes
Round difficulty - Medium

The round had quantitative questions along with some logical reasoning and english section and fundamentals of DBMS ,OS and Data structures and some other such topics

Q1. Can you explain the various disk scheduling algorithms used in operating systems?
Ans. 
Disk scheduling algorithms manage the order in which read/write requests are serviced on a disk.
• Common disk scheduling algorithms include FCFS, SSTF, SCAN, C-SCAN, LOOK, and C-LOOK.

• FCFS (First-Come, First-Served) serves requests in the order they arrive.

• SSTF (Shortest Seek Time First) prioritizes the request closest to the current head position.

• SCAN moves the disk arm from one end to the other, serving requests along t...read more
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Round duration - 90 minutes
Round difficulty - Medium

The editor and the environment was great and not disturbing like many have.
They had their own test cases to check the scope of our code.

Q1. 
Maximum Subarray Sum Problem Statement
Given an array of numbers, the task is to find the maximum sum of any contiguous subarray of the array.
Input:
The first line of input contains the size of the arr...read more
Ans. 
Find the maximum sum of any contiguous subarray in an array of numbers in O(N) time.
• Use Kadane's algorithm to find the maximum subarray sum in O(N) time.

• Initialize two variables: maxEndingHere and maxSoFar to keep track of the maximum sum.

• Iterate through the array and update the variables accordingly.

• Return the maxSoFar as the result.
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Round duration - 40 minutes
Round difficulty - Medium

It had only mcq questions but we could not navigate through the questions it had some reasoning and some dbms topics along with data structure ,memory ,cache memory and other topics

Q1. How do you find the age of an employee from the personal details table in SQL?
Ans. 
To find the age of an employee from the personal details table in SQL, you can calculate the difference between the current date and the employee's birthdate.
• Use the DATEDIFF function in SQL to calculate the difference between the current date and the employee's birthdate.

• Divide the result by 365 to get the age in years.

• Consider leap years for more accurate results.
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Round duration - 10 minutes
Round difficulty - Medium

The interviewer was polite and asked few questions from data structures and some from DBMS and some web question and about my project.

Q1. What is the difference between a primary key and a candidate key in a database management system?
Ans. 
Primary key uniquely identifies a record in a table, while candidate key can also uniquely identify a record but is not chosen as primary key.
• Primary key is chosen as the main unique identifier for a table

• Candidate key is a unique key that could also be chosen as primary key

• A table can have multiple candidate keys but only one primary key

• Example: In a table of students, 'student_id' could be a primary key while 'email'...read more
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Round duration - 12 minutes
Round difficulty - Medium

The interviewer asked me about my project and told me to describe myself in one word and justify that and asked my personal skills and asked some technical questions as well

Q1. What is pickling?
Ans. 
Pickling is a process of preserving or extending the shelf life of food by storing it in a solution of salt, vinegar, or brine.
• Pickling involves submerging food in a solution of salt, vinegar, or brine to preserve it.

• Common examples of pickled foods include cucumbers (pickles), onions, and cabbage.

• Pickling can also enhance the flavor of food by infusing it with spices and herbs.

• The acidity of the pickling solution help...read more
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Q1. Screening round: it just like the formality round Just talk about yourself and your projects
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Q1. Just ask fundamental questions of flutter
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Q1. It was F2F HR round Discuss about salary
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Q1. What is Optional chaining ?
Ans. 
Optional chaining allows safe access to deeply nested object properties without causing runtime errors if a property is undefined or null.
• Prevents runtime errors when accessing properties of an object that may not exist.

• Syntax: Use the '?' operator before accessing a property, e.g., obj?.property.

• Example: const name = user?.profile?.name; // returns undefined if user or profile is null.

• Can be used with function calls: ...read more
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Q2. What is Debouncing?
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