Big Oh Notation SDE (Software Development Engineer) 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
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
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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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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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Q1. Diff btw vite and webpack
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Q2. What is currying in js
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Q1. What is currying in javascript?
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Q2. Diff btw webpack and vite
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Q1. Difference between function and method
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Q2. A program related to strings
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Q3. A program related to prime numbers
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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. Tell Me about yourself
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Q2. What is C# and coding.
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Q1. What is your CCTC?
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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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Give 10 questions from node js backend

Q1. Ask about angular and node js
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Q2. What is package.json
Ans. 
package.json is a file used in Node.js projects to manage dependencies, scripts, and metadata.
• It is a JSON file that contains information about the project, such as name, version, dependencies, and scripts.

• It is used to manage project dependencies by listing them in the 'dependencies' and 'devDependencies' fields.

• It allows developers to define scripts for tasks like building, testing, and running the project.

• Example: {...read more
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Q3. What is components in angular,how share data to component
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Components in Angular are building blocks of an application. Data can be shared between components using input properties and output events.
• Components in Angular are reusable, self-contained units of code that define a part of the user interface.

• Data can be shared to a component using input properties, where data is passed from the parent component to the child component.

• Data can also be shared from a child component t...read more
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Q4. What is === and == ,and wher use === is real time projects
Ans. 
=== is strict equality operator, while == is loose equality operator. === is commonly used in real-time projects for accurate comparisons.
• === is a strict equality operator that checks both value and type of operands

• == is a loose equality operator that only checks the value of operands

• === is commonly used in real-time projects to ensure accurate comparisons and prevent unexpected type coercion issues
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Q5. Write arrow function syntax
Ans. 
Arrow function syntax in JavaScript
• Arrow functions are concise syntax for writing function expressions in JavaScript

• They have a shorter syntax compared to traditional function expressions

• They do not have their own 'this', 'arguments', 'super', or 'new.target' keywords
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Q6. What is difference between arrow function and anonymous function
Ans. 
Arrow functions are concise syntax for writing function expressions, while anonymous functions do not have a name.
• Arrow functions have a shorter syntax compared to anonymous functions.

• Arrow functions do not have their own 'this' keyword, while anonymous functions do.

• Arrow functions do not have 'arguments' object, while anonymous functions do.

• Arrow functions are not hoisted, while anonymous functions are hoisted.
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