PayPal – Node JS Interview Questions

Here is the list of Node JS Interview Questions which are recently asked in PayPal company. These questions are included for both Freshers and Experienced professionals. Our Node JS Training has Answered all the below Questions.

1. What is Node.js? Where can you use it?

Node JS is a platform built on Chrome's JavaScript runtime for easily building fast and scalable network applications. It is primarily used for non-blocking, event-driven servers, due to its single-threaded nature.

2. Why use Node.js?

Node JS is used for non-blocking, event-driven servers, due to its single-threaded nature. It's used for traditional web sites and back-end API services, but was designed with real-time, push-based architectures in mind.

3. What Is Purpose Of Buffer Class In Node?

Buffer class provides instances to store raw data similar to an array of integers but corresponds to a raw memory allocation outside the V8 heap. It is a global class that can be accessed in an application without importing the buffer module.

4. What Is Piping In Node?

The readable.pipe() method in a Readable Stream is used to attach a writable stream to the readable stream so that it consequently switches into flowing mode and then pushes all the data that it has to the attached Writable. Syntax: readable.pipe( destination, options ).

5. Which Module Is Used For File Based Operations?

Node JS gives the functionality of file I/O by providing wrappers around the standard POSIX functions. All file system operations can have synchronous and asynchronous forms depending upon user requirements.

6. Which Module Is Used For Buffer Based Operations?

Buffer module is used for buffer based operations.Buffer class is a global class that can be accessed in an application without importing the buffer module.

7. Which Module Is Used For Web Based Operations?

http module is used for web based operations. fs module provides both synchronous as well as asynchronous methods.

8. What Are Streams?

Streams are one of the fundamental concepts that power Node. JS applications. They are data-handling method used to read or write input into output sequentially. It is a way to handle reading/writing files, network communications, or any kind of end-to-end information exchange in an efficient way.

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9. How Many Types Of Streams Are Present In Node?

There are four types of streams in Node. Node JS Streams

Readable is used for read operations.
Writable is used for write operations.
Duplex can be used for both read and write operations.
Transform: It is type of duplex stream where the output is computed according to input.

10. Name Some Of The Events Fired By Streams.

Data event is fired when there is data is available to read.
End event is fired when there is no more data to read.
Error event is fired when there is any error receiving or writing data.
Finish event is fired when all the data has been flushed to underlying system.

11. What Is Chaining In Node?

There are two most commonly used methods for chaining functions provided by the async module: parallel(tasks, callback) is a collection of functions that runs parallel in practice through I/O switching. Series (tasks, callback): Each function in tasks run only after the previous function is completed.

12. How Will You Open A File Using Node?

Filename: It holds the name of the file to read or the entire path if stored at other location.Flag: The operation in which file has to be opened.mode: Sets the mode of file i.e. r-read, w-write, r+ -readwrite. callback: It is a callback function that is called after reading a file.

13. How Will You Read A File Using Node?

Node. js | fs. readFile() Method

Filename: It holds the name of the file to read or the entire path if stored at other location.
Encoding: It holds the encoding of file and its default value is 'utf8'.
callback_function: It is a callbackfunctiion that is called after reading of file. It takes two parameters:

14. How Will You Delete A File Using Node?

To delete a file in Node.JS, Node FS unlink(path, callback) can be used for asynchronous file operation and unlinkSync(path) can be used for synchronous file operation.

15. How Will You Create A Directory?

Streams are one of the fundamental concepts that power Node.JS applications. They are data-handling method and are used to read or write input into output sequentially. It is a way to handle reading/writing files, network communications, or any kind of end-to-end information exchange in an efficient way.

16. Why To Use Node.js?

The few reasons to use Node JS

Scalability is one of the key advantages of Node.
Ease of Use: It is open-source and easy to use.
Community and Fast
Modern: It is suitable for building all types of web applications, especially, real-time web applications where scalability is an important factor.

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TOP MNC's NODE JS INTERVIEW QUESTIONS & ANSWERS

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PayPal Node JS Interview Questions