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Sarthak Srivastava

Project Manager and AI-assisted product builder working across product flow, automation logic, integrations, and delivery.

Engineered with Next.js 16, React 19 and Architectural Precision.
© 2026 Sarthak Srivastava.

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React

45 Topics

Introduction to React Project Setup JSX Your First Component

Roadmap →Cheatsheet →Interview Q&A →

LearnReact

⚛️

FrontendIntermediate

React

React is the most widely used JavaScript library for building user interfaces. Created by Meta (Facebook), it powers Facebook, Instagram, WhatsApp Web, Netflix, Airbnb, and thousands of other web applications. This track covers React from first component to advanced performance optimization, testing, and integration with Next.js.

155+ Topics

8–12 weeks

6–28 LPA

Start Learning →View Roadmap

Getting Started

Introduction to React

What is React, history, virtual DOM, component-based architecture

Create React App, Vite, Next.js, project structure, npm vs pnpm

JavaScript XML syntax, expressions, fragments, JSX compilation, differences from HTML

Your First Component

Functional components, component naming, default export, rendering

Core Concepts

Functional vs class components, pure components, component composition

Passing props, prop types, default props, destructuring, children prop

State & useState

useState hook, state updates, batching, functional updates, immutability

Synthetic events, event handlers, passing arguments, preventing defaults

Conditional Rendering

if/else, ternary, &&, nullish coalescing, switch patterns

Rendering arrays, the key prop, index vs stable IDs, reconciliation

Controlled vs uncontrolled components, input, select, textarea, form submission

Lifting State Up

Shared state, lifting to parent, data flow, sibling communication

React Hooks

State declaration, update patterns, lazy initializer, state batching in React 18

Side effects, dependency array, cleanup, timing vs lifecycle comparison

Context API, createContext, Provider, useContext, when to use vs props

DOM references, mutable values, forwardRef, useImperativeHandle

Expensive calculations, memoization, when to use, over-memoization pitfalls

Memoizing callbacks, referential equality, use with useEffect and child components

Complex state, reducer pattern, action objects, dispatch, vs useState

Creating custom hooks, naming conventions, sharing logic, examples (useLocalStorage, useFetch)

useTransition & useDeferredValue

Concurrent features, non-urgent updates, avoiding UI freeze

Generating unique IDs for accessibility, SSR-safe IDs

Only call at top level, only call in React functions, ESLint plugin

State Management

Global state without libraries, context structure, performance, when to use

createSlice, configureStore, useSelector, useDispatch, Immer under the hood

Simple stores, selectors, actions, persistence, devtools

Atomic state management, atom, selector, derived state

React Router

React Router Basics

BrowserRouter, Routes, Route, Link, NavLink, v6 API

Advanced Routing

Nested routes, layout routes, params, search params, loader/action pattern

Protected Routes

Authentication guards, redirect, Navigate component

Performance

Component memoization, shallow comparison, when to use, custom comparison

List Virtualization

react-window, react-virtual, windowing large lists

Code Splitting & Lazy Loading

React.lazy, Suspense, dynamic imports, route-based splitting

React DevTools Profiler

Identifying re-renders, flame graph, commit info, wasted renders

React 18 & Server Components

Concurrent Mode

Concurrency in React, time slicing, automatic batching, Suspense improvements

React Server Components

RSC vs client components, serialization, data fetching, use server/client directive

Suspense & Error Boundaries

Streaming SSR, Suspense for data fetching, ErrorBoundary, fallback UI

React 19 Features

use() hook, Server Actions, form actions, optimistic updates, asset loading

Testing

React Testing Library

render, screen, userEvent, queryBy, findBy, accessibility queries

Test setup, describe/it/expect, mocking, async tests, snapshots

Vite-native testing, compatibility with RTL, performance over Jest

Interview Preparation

Beginner Interview Questions

Top 40 React basics for junior frontend interviews

Advanced Interview Questions

Virtual DOM, reconciliation, concurrent features, performance — senior level

200+ MCQs for placement and frontend interview prep

React Cheatsheet

Quick reference for hooks, patterns, and lifecycle mapping

Companies Using React

MetaNetflixAirbnbAtlassianShopifyFlipkartSwiggyZomato