Category: Interview

React.js Logical React.js Logical Interview Questions and Answers 1. How do you prevent unnecessary re-renders in a large React app? Explanation: React re-renders components when props or state change. To avoid unnecessary re-renders, use: React.memo() to memoize components. useMemo() to memoize computed values. useCallback() to memoize functions. This prevents React from re-rendering unless necessary, improving […]

PostgreSQL PostgreSQL Interview Questions and Answers Section 1: PostgreSQL Architecture & Internals (20+ Questions) 1. What is the architecture of PostgreSQL? PostgreSQL follows a client-server model. It consists of the following key components: Postmaster (master process) Backend Server Processes (handle queries) Shared Buffers WAL (Write-Ahead Logging) Background Writer and Checkpointer 2. What is a WAL […]

Redis Redis Interview Questions and Answers What is Redis? – Redis is an in-memory, key-value data store known for high performance, supporting data structures such as strings, hashes, lists, sets, sorted sets. What data types does Redis support? – Strings, Lists, Sets, Sorted Sets (zsets), Hashes, Bitmaps, HyperLogLogs, Streams, and Geospatial indexes. How do you […]

DOCKER DOCKER Interview Questions and Answers 1. What is Docker, and how is it different from a virtual machine? Answer: Docker is a platform for developing, shipping, and running applications in containers. Unlike virtual machines (which virtualize hardware), Docker virtualizes the OS, making it lightweight and faster to start. Feature Virtual Machine Docker Virtualizes Hardware […]

DSA DSA Interview Questions and Answers 1. Find the First Non-Repeating Character in a String Problem: Given a string s, find the first non-repeating character and return its index. If none exists, return -1. JavaScript: function firstUniqChar(s) { const freq = {}; for (let char of s) { freq[char] = (freq[char] || 0) + 1; […]

MongoDB MongoDB Interview Questions and Answers SECTION 1: MongoDB Basics & Core Concepts 1. What is MongoDB and how does it differ from traditional RDBMS? MongoDB is a NoSQL, document-oriented database that stores data in BSON (Binary JSON) format. Unlike RDBMS (Relational Database Management Systems), MongoDB does not rely on tables and rows. Instead, it […]

Node.js & Express.js Node.js & Express.js​ Interview Questions and Answers Section 1: Core Node.js Concepts (20+ Questions) 1. What is the event loop in Node.js? The event loop is the mechanism that allows Node.js to perform non-blocking I/O operations by offloading operations to the system kernel. It continuously checks the call stack and callback queue […]

React.js & Next.js React.js & Next.js​ Interview Questions and Answers Section 1: React Core Concepts 1. What is JSX? Answer: JSX (JavaScript XML) is a syntax extension for JavaScript used with React to describe UI elements. const element = <h1>Hello, world!</h1>; JSX gets transpiled to React.createElement calls. 2. Explain Virtual DOM. Answer: Virtual DOM is […]

TYPESCRIPT TYPESCRIPT Interview Questions and Answers What is TypeScript? TypeScript is an open-source language developed by Microsoft that builds on JavaScript by adding static type definitions. These types provide a way to describe the shape of objects, providing better documentation and allowing TypeScript to validate your code. It helps catch errors early through a type […]

JAVASCRIPT JAVASCRIPT Interview Questions and Answers Basics and Core Concepts What are JavaScript data types? JavaScript has 7 primitive data types: undefined, null, boolean, number, string, symbol, and bigint. Objects are non-primitive data types. js// Primitive let name = “Ram”; // String let age = 25; // Number let isOnline = true; // Boolean let […]