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
Ans. 
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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Aptitude, core concepts and a code

Q1. What is the one thing you learnt from college club?
Ans. 
I learned the importance of teamwork and collaboration from my college club.
• Developed strong communication skills by working with diverse group of individuals

• Learned how to delegate tasks effectively to achieve common goals

• Gained experience in problem-solving and conflict resolution through group projects
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Q2. What is the one thing you want to expereince?
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I want to experience living in a different country and immersing myself in a new culture.
• Traveling to a foreign country and learning about their customs and traditions

• Trying new foods and experiencing different ways of life

• Making friends with locals and exploring the local attractions
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Q1. Difference between relational and non relational dbms
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Relational DBMS stores data in tables with predefined relationships, while non-relational DBMS stores data in flexible, schema-less formats.
• Relational DBMS uses structured query language (SQL) for querying data

• Non-relational DBMS can store data in various formats like key-value pairs, document-based, graph databases

• Relational DBMS ensures data integrity through normalization and constraints

• Non-relational DBMS offers be...read more
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Q2. Difference betweeen class,abstract class,interface in python
Ans. 
Class is a blueprint for creating objects, abstract class cannot be instantiated and can have abstract methods, interface is a contract for classes to implement certain methods.
• Class is a blueprint for creating objects with attributes and methods.

• Abstract class cannot be instantiated and can have abstract methods that must be implemented by subclasses.

• Interface is a contract for classes to implement certain methods, bu
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Q3. Project related questions were asked
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Q1. Context api, js related qstns, simple programming qstn,
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Q2. Remove duplicates without using set.
Ans. 
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. Basics of java like string ,string builder ,Buffer,scp
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Q2. Spring boot annotaions
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