Rannlab Technologies Node JS Developer Interview Questions and Answers

Find 2nd repeated character from string in JS.

Q1. What is nodejs, explain the event loop.
Ans. 
Node.js is a JavaScript runtime built on Chrome's V8 JavaScript engine. It allows developers to run JavaScript on the server-side.
• Node.js is event-driven and non-blocking I/O model.

• It uses an event loop to handle asynchronous operations.

• The event loop is a continuously running process that waits for events and executes callbacks.

• Callbacks are functions that are called when an event occurs, such as a request completing ...read more
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Q2. What is event loop ?
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Event loop is a mechanism that allows Node.js to perform non-blocking I/O operations.
• Event loop is a single-threaded loop that constantly checks for new events in the event queue.

• It executes the callback functions associated with the events in the queue.

• It allows Node.js to handle multiple requests simultaneously without blocking the execution of other requests.

• It is responsible for managing the order of execution of t...read more
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Q3. What is the role of libuv ?
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libuv is a multi-platform support library with a focus on asynchronous I/O.
• libuv provides event loop, thread pool, timer, and file system APIs.

• It is used by Node.js to handle I/O operations in a non-blocking way.

• libuv abstracts the differences between operating systems and provides a consistent API.

• It also supports network programming and inter-process communication.

• Examples of libuv-based applications include Node.js,
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Q1. What is the difference between cluster and thread ?
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Cluster is a group of processes that share the same resources while thread is a lightweight process that shares the same memory.
• Cluster is used for scaling and load balancing while thread is used for improving performance.

• Cluster can run on multiple machines while thread runs within a single process.

• Cluster requires inter-process communication while thread does not.

• Examples of cluster include PM2 and Node.js cluster mo...read more
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Q1. Run time polymorphism code
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Q2. Linked list code
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Q3. Deep copy shallow copy differences
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Deep copy creates a new copy of an object with its own unique memory space, while shallow copy creates a new object that references the same memory locations as the original object.
• Deep copy duplicates all nested objects, while shallow copy only duplicates the references to nested objects.

• Deep copy ensures that changes to the copied object do not affect the original object, while shallow copy may lead to unintended sid...read more
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Q1. More deep questions about polymorphism code
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Q2. Code for interchange of strings without strcpy
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Use a loop to swap characters of two strings without using strcpy function.
• Create two arrays of characters to store the strings

• Use a loop to iterate through each character of the strings and swap them

• Ensure to handle cases where strings have different lengths
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Q1. Given an array {1, 2, 1, 4, 5, 4, 8, 7}, how can you use Streams to remove duplicates while retaining only the even numbers?
Ans. 
Use Streams to remove duplicates and retain only even numbers from an array.
• Convert the array to a stream using Arrays.stream()

• Use distinct() to remove duplicates

• Filter out odd numbers using filter()

• Collect the result using collect(Collectors.toList())
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Q2. What is the use of Static and final when you will use Static methods
Ans. 
Static methods can be accessed without creating an instance of the class, while final keyword makes the method unchangeable.
• Static methods belong to the class itself, not to any specific instance

• Final keyword ensures that the method cannot be overridden in subclasses

• Static methods are commonly used for utility methods that do not require access to instance variables

• Example: Math class in Java has static methods like Ma
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Q3. What is the difference between @restController and @controller Annotation
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The @RestController annotation is used to define RESTful web services while @Controller annotation is used to define MVC controller.
• RestController is a specialized version of Controller used for RESTful web services

• RestController eliminates the need for @ResponseBody annotation

• Controller is used for traditional MVC controller functionality

• RestController returns data directly without needing to go through a view resolve...read more
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Q4. What is microservices why we use it
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Microservices are a software development technique where applications are composed of small, independent services that communicate with each other.
• Microservices allow for easier scalability and maintenance of complex applications.

• Each service in a microservices architecture can be developed, deployed, and scaled independently.

• Microservices promote flexibility and agility in software development.

• Examples of companies us...read more
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Q1. Context api, js related qstns, simple programming qstn,
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Q2. Remove duplicates without using set.
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Remove duplicates from array of strings without using set.
• Iterate through the array and compare each element with all other elements to find duplicates.

• Create a new array and add elements only if they are not already present in the new array.
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A standard online test conducted through one of the testing platforms.

Q1. Java 8 features
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Q2. Rest API
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Q3. Java 8 coding problem
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Q4. Collections
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Q1. It was based on my previous project
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Q1. What are primitive and non primitive data types
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Primitive data types are basic data types provided by the programming language, while non-primitive data types are created by the programmer.
• Primitive data types include int, float, double, char, boolean, etc.

• Non-primitive data types include arrays, classes, interfaces, etc.

• Primitive data types store actual values, while non-primitive data types store references to objects.
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Q2. What are access modifiers and non access modifiers
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Access modifiers control the visibility of classes, methods, and variables. Non-access modifiers provide additional functionality.
• Access modifiers: public, private, protected, default

• Non-access modifiers: static, final, abstract, synchronized

• Example: public class MyClass { private int myVar; }
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Q3. What are all Java 8 features and explain the one which we have used in our project
Ans. 
Java 8 features include lambda expressions, functional interfaces, streams, and more.
• Lambda expressions allow concise syntax for defining anonymous functions.

• Functional interfaces can have only one abstract method and are used for lambda expressions.

• Streams provide a way to process collections of objects in a functional style.

• Optional class helps to avoid NullPointerException by wrapping a value that may be null.
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Q4. CICD tools which we have used explain in high level
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CICD tools automate the process of building, testing, and deploying code changes.
• Popular CICD tools include Jenkins, GitLab CI/CD, CircleCI, and Travis CI

• These tools help in automating the software development lifecycle

• They enable continuous integration, continuous delivery, and continuous deployment

• CICD tools help in improving code quality, reducing manual errors, and increasing development speed
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Q5. What is containerization
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Containerization is a lightweight, portable, and self-sufficient way to package and run applications.
• Containerization involves encapsulating an application and its dependencies into a container image.

• Containers are isolated from each other and share the host OS kernel.

• Popular containerization platforms include Docker and Kubernetes.

• Containerization allows for easy deployment and scaling of applications.
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Q6. What is indexing in sql
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Indexing in SQL is a technique used to improve the performance of queries by creating a data structure that allows for faster retrieval of data.
• Indexes are created on columns in a database table to speed up the retrieval of rows that match a certain condition in a query.

• They work similar to the index in a book, allowing the database to quickly locate the rows that satisfy the query.

• Indexes can be created using a single...read more
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Q7. Programming question on stream like finding the longest string in a given list of string
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SQL , CODING QUESTION PYTHON

Q1. BASIC SQL QUESTIOS
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Q2. OOPS 4 PILLARS INHERITANCE ETC
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Q1. TELL ME ABOUT YOURSELF
Ans. 
I am a software developer with 5 years of experience in Java, Python, and SQL.
• 5 years of experience in Java, Python, and SQL

• Strong problem-solving skills

• Experience working in Agile development environment

• Familiarity with version control systems like Git

• Passionate about learning new technologies
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Q2. WHAT DO YOU KNOW ABOUT YOUR COMPANY
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Company is a leading software development firm specializing in creating innovative solutions for various industries.
• Company has a strong reputation for delivering high-quality software products

• Specializes in creating custom solutions for clients in different industries

• Known for innovative and cutting-edge technology solutions

• Has a diverse portfolio of successful projects

• Company values teamwork and collaboration in thei
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