Infosys Node JS Developer Interview Questions and Answers

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 I/O operations without blocking the execution of other code

• Event loop continuously checks the event queue for new events to process

• Callbacks are used to handle the completion of asynchronous operations

API Gateway in AWS is a fully managed service that makes it easy for developers to create, publish, maintain, monitor, and secure APIs at any scale.

• API Gateway allows you to create RESTful APIs that can be integrated with other AWS services like Lambda, DynamoDB, and S3.

• It provides features like authentication, authorization, rate limiting, and caching to improve API performance and security.

• API Gateway can also be use...read more

Swagger is a tool for designing, building, and documenting APIs. Adding authentication in Swagger involves using security definitions and security requirements.

• Swagger is a tool used for designing, building, and documenting APIs

• To add authentication in Swagger, you can use security definitions to define authentication methods like API keys, OAuth, etc.

• You can then specify security requirements in your Swagger documenta...read more

A callback function in NodeJS is a function that is passed as an argument to another function and is executed later.

• Callback functions are commonly used in asynchronous programming in NodeJS.

• They allow us to handle the result of an asynchronous operation once it is completed.

• Callback functions can be defined inline or as separate named functions.

• They are often used with functions like setTimeout, readFile, and database...read more

The setTimeout function in JavaScript is used to schedule a task to be executed after a specified delay.

• The setTimeout function takes two parameters: a callback function and a delay time in milliseconds.

• The callback function is executed after the specified delay.

• The setTimeout function returns a unique identifier (timer ID) that can be used to cancel the execution of the callback function using the clearTimeout functio...read more

OAuth is an open standard for authorization that allows users to grant access to their data without sharing their credentials.

• OAuth is used to authenticate and authorize users in applications.

• It allows users to grant limited access to their data to third-party applications.

• OAuth uses tokens to grant access instead of sharing credentials.

• The OAuth flow involves the client, server, and the authorization server.

• Popular OA...read more

To connect to MongoDB from NodeJS backend, use the 'mongodb' package and the 'MongoClient' class.

• Install the 'mongodb' package using npm: npm install mongodb

• Require the 'mongodb' package in your NodeJS file: const MongoClient = require('mongodb').MongoClient

• Create a connection URL with the appropriate MongoDB server details: const url = 'mongodb://localhost:27017/mydatabase'

• Use the 'MongoClient' class to connect to the...read more

SQL command to get the TOP 3 list in a data set

• Use the SELECT statement to retrieve data from the table

• Use the ORDER BY clause to sort the data in descending order

• Use the LIMIT clause to limit the result set to 3 rows

Terraform is used to automate infrastructure provisioning and management.

• Terraform is a tool for defining and provisioning infrastructure as code.

• It allows you to create, modify, and destroy infrastructure resources using declarative configuration files.

• Terraform supports various cloud providers like AWS, Azure, and GCP.

• You can define infrastructure resources such as virtual machines, networks, and storage using Terraf...read more

I implemented Docker and Kubernetes to containerize and orchestrate my NodeJS applications.

• I used Docker to create containers for my NodeJS applications, ensuring consistency and portability.

• I wrote Dockerfiles to define the environment and dependencies for each application.

• I used Docker Compose to define and manage multi-container applications.

• I used Kubernetes to orchestrate and manage the deployment, scaling, and mo...read more

AWS Mesh is a service mesh that provides secure communication between microservices in a containerized application.

• AWS Mesh is built on top of AWS App Mesh, which is a managed service for service mesh architecture.

• It allows developers to easily monitor and control the communication between microservices.

• AWS Mesh provides features like traffic routing, load balancing, service discovery, and observability.

• It supports var...read more

API is a set of rules and protocols for building and interacting with software applications. Schema defines the structure of data in a database.

• API stands for Application Programming Interface, it defines how software components should interact.

• APIs can be used to access data or functionality from external sources, such as a web server or database.

• Schema defines the structure of data in a database, including tables, fi...read more