Lumbini Elite Solutions & Services Senior Software Developer Interview Questions and Answers

Q1. What is Virtual DOM, Explain ?
Ans. 
Virtual DOM is a concept in web development where a lightweight copy of the actual DOM is created and manipulated for efficient rendering.
• Virtual DOM is an abstraction of the real DOM.

• It is used in frameworks like React to improve performance.

• Changes made to the virtual DOM are compared with the actual DOM, and only the necessary updates are applied.

• This approach reduces the number of direct manipulations on the actual...read more
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Q2. What is Higher Order Component ?
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Higher Order Component is a function that takes a component and returns a new component with additional functionality.
• Higher Order Components (HOCs) are a pattern in React for reusing component logic.

• They are functions that accept a component and return a new component with enhanced capabilities.

• HOCs can be used for cross-cutting concerns like authentication, logging, or data fetching.

• They enable code reuse, compositio...read more
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Q3. Life Cycle Methods in React
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Life Cycle Methods in React
• React components have several life cycle methods that are called at different stages of a component's life

• These methods allow developers to perform actions like initializing state, fetching data, and updating the UI

• Some commonly used life cycle methods are componentDidMount, componentDidUpdate, and componentWillUnmount
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Q1. Palindrome code should design
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Palindrome code should be designed to check if a given string is the same forwards and backwards.
• Create a function that takes a string as input

• Remove any spaces and punctuation from the string

• Reverse the string and compare it to the original string to check if it is a palindrome
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Q2. Regarding sql topics like joins and acid
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Q3. Project explain and domain
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Q4. Project explain and domain and internal working
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Q5. Oops concepts and coding
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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
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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?
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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?
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
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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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The aptitude test was relatively straightforward, consisting of both aptitude and technical questions, with a difficulty level ranging from easy to medium.

Q1. Was asked to write a code on basic DSA concept
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Q2. Then was asked basic questions on DSA and SQL
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Q1. Number series in aptitude
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Number series in aptitude involves identifying the pattern in a sequence of numbers and predicting the next number.
• Look for patterns such as arithmetic progression, geometric progression, or a combination of both.

• Check for alternate numbers, differences between consecutive numbers, or multiplication factors.

• Consider prime numbers, squares, cubes, or other mathematical operations applied to the series.

• Example: 2, 4, 6, ...read more
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Q2. Relation ships in berbal
Ans. 
Relationships in verbal communication are crucial for effective collaboration and understanding.
• Verbal communication involves both verbal and non-verbal cues

• Active listening is key to building strong relationships in verbal communication

• Clarity and conciseness in speech can enhance relationships

• Empathy and understanding of others' perspectives are important in verbal relationships
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Q1. Explain the four branches of oops
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The four branches of OOP are encapsulation, inheritance, polymorphism, and abstraction.
• Encapsulation: Bundling data and methods that operate on the data into a single unit.

• Inheritance: Allowing a class to inherit properties and behavior from another class.

• Polymorphism: The ability for objects of different classes to respond to the same method call.

• Abstraction: Hiding the complex implementation details and showing only
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Q2. Explain about the structures in c
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Structures in C are user-defined data types that allow grouping of variables of different data types under a single name.
• Structures are used to represent a record which consists of different data types.

• They are defined using the 'struct' keyword.

• Each variable in a structure is called a member.

• Structures can be nested within other structures.

• Example: struct employee { int emp_id; char emp_name[50]; float emp_salary; };

• E
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Q1. What is react why it's used?
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Q1. What is virtual DOM in react?
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Filter and shot the filter block based on title using redux?

Q1. What is the difference between an abstract class and an interface in object-oriented programming?
Ans. 
Abstract class can have both abstract and non-abstract methods, while interface can only have abstract methods.
• Abstract class can have method implementations, while interface cannot.

• A class can implement multiple interfaces, but can only inherit from one abstract class.

• Interfaces are used to define contracts for classes to implement, while abstract classes are used to provide a common base for subclasses.

• Example: Abstr...read more
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Q2. Abstract classes can have implemented methods; interfaces can only have declarations (before JAVA 8).
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Q1. 3 Question was there related to architecture and Computer networks.
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Q1. Microservices and Monolith.
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Q2. Leetcode hard Sum.
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