Node JS Developer
30+ Node JS Developer Interview Questions and Answers for Freshers
Q1. 2. What are the main modules of Node.js? Explain in detail.
The main modules of Node.js are HTTP, File System, Path, and Events.
HTTP module allows Node.js to transfer data over the HyperText Transfer Protocol (HTTP).
File System module enables interaction with the file system, allowing reading, writing, and manipulating files.
Path module provides utilities for working with file and directory paths.
Events module allows for event-driven programming, enabling the creation and handling of custom events.
Q2. 1. What is Node.js? Describe the inner workings of Node.js
Node.js is a JavaScript runtime built on Chrome's V8 JavaScript engine, used for server-side and networking applications.
Node.js is an open-source, cross-platform runtime environment for executing JavaScript code outside of a browser.
It uses an event-driven, non-blocking I/O model that makes it lightweight and efficient.
Node.js allows developers to build scalable and high-performance applications.
It provides a rich set of built-in modules and libraries for various functionali...read more
Q3. How does Nodejs differentiate and handle synchronous and asynchronous task
Node.js uses event-driven architecture to handle asynchronous tasks while synchronous tasks are executed in a blocking manner.
Node.js uses event loop to handle asynchronous tasks by offloading them to the system, allowing other tasks to continue without waiting.
Synchronous tasks are executed in a blocking manner, meaning the program waits for each task to complete before moving on to the next one.
Node.js provides non-blocking I/O operations which allow multiple tasks to be ex...read more
Q4. What is NodeJs , ServerSide,Redux,flex,mongo, Expresss
NodeJs is a JavaScript runtime built on Chrome's V8 JavaScript engine. ServerSide is a term used to describe code that runs on the server side. Redux is a predictable state container for JavaScript apps. Flex is a CSS layout model. Mongo is a NoSQL database. Express is a web application framework for Node.js.
NodeJs is a runtime environment that allows you to run JavaScript on the server side.
ServerSide refers to code that is executed on the server rather than the client side....read more
Q5. What do you know about NodeJS?
NodeJS is a server-side JavaScript runtime built on Chrome's V8 JavaScript engine.
NodeJS allows developers to build scalable and high-performance applications.
It uses an event-driven, non-blocking I/O model that makes it lightweight and efficient.
NodeJS has a large and active community with a vast number of open-source modules available.
It is commonly used for building web applications, APIs, real-time chat applications, and more.
NodeJS can be easily integrated with other tec...read more
Q6. Difference between public, private, protected access modifiers.
Public, private, and protected are access modifiers used in object-oriented programming to control the visibility of class members.
Public: accessible from outside the class
Private: only accessible within the class
Protected: accessible within the class and its subclasses
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Q7. How to make Nodejs handle multiple thread
Node.js is single-threaded, but can handle multiple threads using child processes or worker threads.
Use child processes to run multiple instances of Node.js
Use worker threads for CPU-intensive tasks
Leverage the cluster module to create a pool of worker processes
Q8. Why use node js,why NodeJs is single thread
Node.js is used for its non-blocking, event-driven architecture. It is single-threaded to optimize performance.
Node.js is popular for its asynchronous, non-blocking I/O model which allows for handling multiple requests efficiently.
Being single-threaded, Node.js can handle a large number of connections without the overhead of creating a new thread for each request.
Node.js uses event-driven architecture and callbacks to handle requests, making it highly scalable and performant....read more
Node JS Developer Jobs
Q9. How do you deploy your application
I deploy my application using containerization and continuous integration/continuous deployment (CI/CD) pipelines.
Utilize Docker to containerize the application for easy deployment and scalability
Use CI/CD pipelines such as Jenkins or GitLab CI to automate the deployment process
Deploy to cloud platforms like AWS, Azure, or Google Cloud for reliable hosting
Implement monitoring and logging tools like Prometheus and ELK stack for performance tracking
Q10. What is apply , call ,bind method?
apply, call, and bind are methods used to manipulate the context of a function in JavaScript.
apply() - calls a function with a given 'this' value and arguments provided as an array
call() - calls a function with a given 'this' value and arguments provided individually
bind() - creates a new function that, when called, has its 'this' keyword set to the provided value
Q11. Fork vs spawn and when you used this
Fork creates a new process while spawn launches a new process asynchronously.
Fork is used to create child processes in Node.js, typically for running separate instances of the same application.
Spawn is used to launch a new process asynchronously, allowing for communication between the parent and child processes.
Fork is commonly used in cluster mode for load balancing in Node.js applications.
Spawn is used for executing external commands or scripts in Node.js.
Q12. How to implement caching using rabitmq
Caching can be implemented using RabbitMQ by storing frequently accessed data in memory.
Set up a RabbitMQ server to act as a message broker
Publish data to RabbitMQ when it is fetched from the database
Subscribe to messages in your Node.js application and store the data in memory
Check the cache before fetching data from the database
Q13. What clinical research?
I'm sorry, but the question is not related to the job position of Node JS Developer.
The question is not relevant to the job position.
It is important to stay focused on the job requirements.
If you are unsure about a question, it is okay to ask for clarification.
Q14. How many types of classes ?
There are two types of classes in Node JS: ES6 classes and prototype-based classes.
ES6 classes are introduced in ES6 (ECMAScript 2015) and provide a more familiar syntax for class-based object-oriented programming.
Prototype-based classes are the traditional way of defining classes in JavaScript, using prototypes to create objects and inherit properties and methods.
Q15. How many types of functions ?
There are two types of functions in JavaScript: named functions and anonymous functions.
Named functions are defined with a function name, such as function myFunction() {}
Anonymous functions are defined without a function name, such as const myFunction = function() {}
Q16. What is Pharmacovilance
Pharmacovigilance is the science and activities related to the detection, assessment, understanding, and prevention of adverse effects or any other drug-related problems.
Pharmacovigilance is the process of monitoring and evaluating the safety and efficacy of drugs.
It involves collecting and analyzing data on adverse drug reactions and other drug-related problems.
Pharmacovigilance helps to ensure that drugs are safe and effective for use by patients.
Examples of pharmacovigilan...read more
Q17. What is event loop in Nodejs?
Event loop in Node.js is a mechanism that allows Node.js to perform non-blocking I/O operations.
Event loop is responsible for handling asynchronous operations in Node.js.
It allows Node.js to perform multiple operations simultaneously without blocking the execution of other code.
Event loop continuously checks the event queue for new events and executes them in a non-blocking manner.
Node.js uses event-driven architecture, where callbacks are executed when events occur.
Example: ...read more
Q18. what is diff bw == and===
The '==' operator checks for equality, while the '===' operator checks for strict equality (including data type).
The '==' operator performs type coercion before comparing two values.
The '===' operator does not perform type coercion and compares both value and data type.
Example: 1 == '1' will return true, but 1 === '1' will return false.
Q19. Explain callback function in node js
A callback function in Node.js is a function passed as an argument to another function, which will be executed at a later time.
Callback functions are commonly used in asynchronous programming in Node.js to handle tasks that take time to complete.
They are passed as arguments to functions that will call them once a certain task is completed.
Callback functions can be used to handle the result of an asynchronous operation, such as reading a file or making an HTTP request.
Example:...read more
Q20. What is NPM in NodeJs
NPM (Node Package Manager) is a package manager for Node.js that allows developers to easily install, manage, and share packages of code.
NPM is used to install and manage dependencies for Node.js projects.
It comes pre-installed with Node.js and allows developers to easily add external libraries and tools to their projects.
NPM uses a file called package.json to keep track of project dependencies and metadata.
Developers can also publish their own packages to the NPM registry fo...read more
Q21. what is asynchorneion
Asynchrony is the ability of a system to handle multiple tasks concurrently without blocking the main thread.
Asynchrony allows tasks to run independently of each other, improving performance and responsiveness.
Node.js uses an event-driven, non-blocking I/O model to handle asynchronous operations.
Examples of asynchronous operations in Node.js include reading files, making network requests, and executing database queries.
Q22. what is spilt methode
The split() method is used to split a string into an array of substrings based on a specified separator.
The split() method takes a separator as an argument, which can be a string or a regular expression.
The method returns an array of substrings created by splitting the original string at each occurrence of the separator.
Example: 'hello world'.split(' ') will return ['hello', 'world']
Q23. What is hoisting in JS
Hoisting is a JavaScript mechanism where variable and function declarations are moved to the top of their containing scope.
Variable and function declarations are hoisted to the top of their scope during the compilation phase.
Only declarations are hoisted, not initializations.
Function declarations take precedence over variable declarations.
Q24. what is deep copy
Deep copy is a copy of an object that duplicates all of its properties and nested objects, creating a new independent copy.
Deep copy creates a new object with all properties and nested objects copied.
Changes made to the original object do not affect the deep copy.
Deep copy is often used when you need to modify an object without affecting the original.
Q25. what are callbacks
Callbacks are functions passed as arguments to other functions, to be executed later.
Callbacks are commonly used in asynchronous programming in Node.js.
They allow functions to be executed after another function has finished its execution.
Callbacks can be used to handle events, make API calls, or perform other tasks asynchronously.
Example: fs.readFile('file.txt', (err, data) => { console.log(data); });
Q26. what is closures
Closures are functions that have access to variables from their outer scope even after the outer function has finished executing.
Closures allow functions to access variables from their parent function even after the parent function has returned.
They help in maintaining state in JavaScript.
Closures are created whenever a function is defined within another function.
Q27. what is promises
Promises in Node.js are objects representing the eventual completion or failure of an asynchronous operation.
Promises are used to handle asynchronous operations in a more readable and manageable way.
They can be in one of three states: pending, fulfilled, or rejected.
Promises can be chained together using .then() to handle success or failure.
They help avoid callback hell and make code more maintainable.
Example: const myPromise = new Promise((resolve, reject) => { ... });
Q28. What is inheritance
Inheritance is a concept in object-oriented programming where a class inherits properties and behaviors from another class.
Inheritance allows a class to reuse code from another class, promoting code reusability and reducing redundancy.
The class that is being inherited from is called the parent class or superclass, while the class that inherits is called the child class or subclass.
Child classes can add new properties and methods, or override existing ones from the parent clas...read more
Q29. Trickiest situation faces
Handling a critical production issue with multiple dependencies failing
Identify the root cause of the issue by analyzing logs and code
Communicate effectively with team members and stakeholders to coordinate a solution
Implement a temporary fix if necessary to minimize impact on users
Q30. What is event loop
Event loop is a mechanism in Node.js that allows non-blocking I/O operations to be performed asynchronously.
Event loop is responsible for handling asynchronous operations in Node.js.
It allows Node.js to perform non-blocking I/O operations efficiently.
Event loop continuously checks the event queue for any pending events to be processed.
It helps in managing the flow of code execution in an asynchronous environment.
Example: setTimeout() function in Node.js uses event loop to sch...read more
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