Sir Biotech Interview Questions and Answers

Yes, I have experience with file upload tasks. Files are saved in DB by storing the file path and retrieval is done by fetching the file path from the DB.

• Used multer middleware in Node.js to handle file uploads

• Saved file path in MongoDB using Mongoose schema

• Retrieved file by querying the database for the file path

• Implemented file upload functionality in a project using React for the front end

They are used in MongoDB aggregation pipeline to perform various operations like joining, filtering, projecting, etc.

• Used in MongoDB aggregation pipeline for data manipulation

• Perform operations like joining, filtering, projecting, etc.

• Help in combining data from multiple collections

• Use $lookup to perform a left outer join between two collections

React hooks are functions that let you use state and other React features in functional components.

• Allow functional components to have state and lifecycle methods

• Replace class components with simpler functional components

• Examples: useState, useEffect, useContext

Developed a real-time chat application using Node.js with Socket.io for instant messaging functionality.

• Implemented server-side logic using Node.js to handle incoming messages and broadcast them to all connected clients

• Utilized Socket.io library to establish WebSocket connections for real-time communication

• Integrated with MongoDB to store chat messages and user information

• Implemented authentication and authorization mechanisms to ensure secure messaging

Redux is a predictable state container for JavaScript apps, used to manage application state in a centralized store.

• Redux helps manage the state of an application in a predictable way

• It allows for a single source of truth for the state of the application

• Redux is commonly used with React to manage the state of components

• Actions are dispatched to update the state in Redux store

• Reducers specify how the state changes in response to actions

CRUD operations in MongoDB include create, read, update, and delete operations on documents in a collection.

• Create: db.collection.insertOne()

• Read: db.collection.find()

• Update: db.collection.updateOne()

• Delete: db.collection.deleteOne()