Elphill Technology Interview Questions and Answers

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
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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
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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
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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?
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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
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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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Total 5 rounds. 1. pen paper coding test at company location (1st one is two pointer and second one is pattern) 2. L1 techinical - oops concept two coding question and some java and advance java concept basic (find palindrome) 3. L2 techinical - two coding question, one puzzle, sql vs nosql, etc (build linked list using class, find min and max element in array), discussion on time complexity 4. L3 managerial round : one basic two loop question and optimmize it , printing pattern question, etc and time complecity 5. HR round- basic hr questions

Q1. Tell me about your self
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Q2. Why are you interested in the role
Ans. 
I am passionate about driving organizational effectiveness and employee engagement through strategic HR initiatives.
• I have a strong background in HR strategy and business partnering

• I enjoy collaborating with cross-functional teams to drive positive change

• I am excited about the opportunity to make a meaningful impact on the organization's culture and performance
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Q3. Talking about Intersted in which things that do in free time
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4 easy level questions will be asked basically from arrays and strings.

Assignment will be given after clearing coding round. In my case ELearning Platform project was given and 7 days time was given to complete.

Q1. DBMS questions like ACID properties, database transaction. Etc
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Q2. Project related questions
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Q3. Basic and conceptual questions of frameworks you know
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Q4. Basic coding questions like armstrong number, palendromic sequence, recursion
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Q1. How would you utilize AWS or Azure services to create scalable web applications
Ans. 
Utilize AWS or Azure services for scalable web applications
• Use AWS Elastic Beanstalk or Azure App Service for easy deployment and scaling

• Leverage AWS Lambda or Azure Functions for serverless computing

• Utilize AWS Auto Scaling or Azure Autoscale to automatically adjust resources based on traffic

• Store data in AWS RDS or Azure SQL Database for scalable database solutions

• Use AWS CloudFront or Azure CDN for content delivery
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Q2. How would you tackle memory leaks if the system your working on was experiencing this issue?
Ans. 
I would use memory profiling tools to identify the source of the leaks and then fix them by properly managing memory allocation and deallocation.
• Use memory profiling tools like Valgrind or Instruments to identify the source of the leaks

• Review the code to ensure proper memory allocation and deallocation practices are being followed

• Implement smart pointers or garbage collection to automatically manage memory

• Use static co...read more
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Q3. Have you worked on legacy systems?
Ans. 
Yes, I have experience working on legacy systems.
• I have successfully maintained and upgraded legacy systems to meet current business needs.

• I have refactored legacy code to improve performance and scalability.

• I have integrated new technologies with legacy systems to enhance functionality.

• I have experience troubleshooting and debugging issues in legacy systems.
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Q1. Are you capable to work with cross functional teams and handle disputes effectively
Ans. 
Yes, I have experience working with cross functional teams and resolving disputes effectively.
• I have successfully collaborated with team members from different departments to achieve project goals.

• I am skilled at mediating conflicts and finding mutually beneficial solutions.

• I prioritize open communication and actively listen to all team members' perspectives.

• I have experience using conflict resolution techniques such a
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