Litmus World Vice President IT Interview Questions and Answers for Experienced

Work-time model and relationship model.

Based on JavaScript and React.

Q1. What are the reasons we should consider hiring you?
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Q2. What contributions do you envision making to our project management efforts?
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Based on my CV, they assigned me a task related to data migration.

Q1. Project reviews
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Q2. Attendance regarding
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Q1. Find the second most occurrence of string.
Ans. 
Find the second most occurrence of string in an array of strings.
• Create a dictionary to store the count of each string in the array

• Sort the dictionary by count in descending order

• Return the key of the second element in the sorted dictionary
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Q1. Rate yourself in js, node js, react, MongoDB (separately)
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Q2. Typeof null, typeof undefined, typeof {}, typeof NaN
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Q3. What changes came in es6
Ans. 
ES6 introduced several new features and improvements to JavaScript, making it more powerful and efficient.
• Arrow functions for more concise syntax

• Let and const for block-scoped variables

• Classes for easier object-oriented programming

• Template literals for easier string interpolation

• Default parameters and rest parameters for function arguments

• Destructuring assignment for easier data extraction

• Promises for asynchronous prog
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Q4. This keyword, closures, hoisting
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Q5. Are let and cont variables hoisted?
Ans. 
Yes, let and const variables are hoisted but not initialized.
• let and const variables are hoisted to the top of their block scope, but they are not initialized until the actual line of code is executed.

• This means that you cannot access a let or const variable before it is declared in the code.

• For example, trying to access a let variable before it is declared will result in a ReferenceError.
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Q6. What is global context
Ans. 
Global context refers to the overall environment or setting in which something exists or operates.
• Global context encompasses all variables, functions, and objects that are accessible throughout an entire program.

• It can be thought of as the 'big picture' view of a program's execution.

• In web development, global context includes the window object in JavaScript.
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Q7. What is temporal deadzone
Ans. 
Temporal dead zone is a period during the variable creation process where accessing the variable results in a ReferenceError.
• Occurs when trying to access a variable before it has been declared with let or const

• Happens due to the variable being in the temporal dead zone until it is declared

• Example: accessing a variable before its declaration will result in a ReferenceError
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Q8. What is modules? types of modules in nodejs
Ans. 
Modules in Node.js are reusable blocks of code that encapsulate related functionality.
• Modules in Node.js can be built-in modules like fs (file system) or third-party modules like express.

• Modules help in organizing code into separate files for better maintainability and reusability.

• Modules can be imported using the require() function in Node.js.
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Q9. Index in mongodb, why we need index, is index good or bad?
Ans. 
Indexes in MongoDB improve query performance by allowing the database to quickly locate and retrieve specific documents.
• Indexes help to speed up query performance by allowing the database to quickly locate specific documents based on the indexed fields.

• Without indexes, MongoDB would have to perform a collection scan, which can be slow and resource-intensive.

• Indexes can be created on single fields or compound fields to ...read more
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Q10. What are hooks , use of useRef
Ans. 
Hooks are a feature in React that allow you to use state and other React features in functional components. useRef is a hook that allows you to create a mutable object that persists for the lifetime of the component.
• Hooks are used to add state and lifecycle methods to functional components in React

• useRef is used to create a mutable reference that persists between renders

• useRef can be used to access DOM elements directl
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Q11. Fs module, http module, worker thread?
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Q12. Why we use mongoose not mongodb driver?
Ans. 
Mongoose is an Object Data Modeling (ODM) library for MongoDB that provides a higher level of abstraction and simplifies interactions with the database.
• Mongoose provides schema validation which helps maintain data integrity.

• Mongoose simplifies querying and data manipulation with built-in functions.

• Mongoose supports middleware functions for pre and post processing of data operations.
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Round duration - 90 minutes
Round difficulty - Easy

Timing was 10:00 AM. Platform was good.

Q1. 
Subarray With Given Sum Problem Statement
Given an array ARR of N integers and an integer S, determine if there exists a contiguous subarray within the array with a sum equal to S. If such a subarray exis...read more
Ans. 
Given an array of integers, find a subarray with a given sum S.
• Iterate through the array while keeping track of the current sum and start index.

• Use a hashmap to store the sum and its corresponding index.

• If the current sum - S is found in the hashmap, a subarray with sum S exists.

• Return the start index and current index as the end index.
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Q2. 
Remove Consecutive Duplicates Problem Statement
Given a string S, your task is to recursively remove all consecutive duplicate characters from the string.
Input:
String S
Output:
Output string
Constr...read more
Ans. 
Recursively remove consecutive duplicate characters from a string.
• Use recursion to check if the current character is the same as the next character, if so skip the next character

• Base case: if string length is 1, return the string

• Example: Input: 'aabbc' Output: 'abc'
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It was done in a group

Done thourgh java and python

Q1. Optimized way to query a column in db with type as long strings. Any method other than indexing?
Ans. 
Consider using full-text search or partitioning the data.
• Utilize full-text search capabilities provided by the database system to efficiently query long strings.

• Consider partitioning the data based on certain criteria to improve query performance.

• Optimize the query by using appropriate data types and indexes for efficient retrieval.
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Q2. What is promise.props and polyfill for promise.all()
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Q1. Leetcode Medium Question -- Container most water
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Q1. LLD, Design patterns, Operating system
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