JavaScript
Intermediate
Master modern JavaScript from foundational syntax, DOM manipulation, and asynchronous programming to browser internals, performance engineering, and enterprise architecture across 3 progressive levels.
0 / 45 lessons
Lessons
45
Complete to finish this stage
Est. time
29.5h
At a comfortable pace
Difficulty
Intermediate
For complete beginners
Why JavaScript Matters
JavaScript is the core programming language of the modern web. It powers user interactions, dynamic rendering, network communication, animations, and full-stack architectures across billions of devices and web applications.
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JavaScript lessons
45 lessons · follow them in order for best results.
JavaScript FundamentalsMaster the foundational concepts of JavaScript: runtime engines, ECMAScript standards, browser vs Node.js environments, execution flow, strict mode, script loading, and debugging tools.Beginner 30 min Level 1 — BeginnerVariablesMaster variable declaration, initialization, scope differences between var, let, and const, hoisting mechanisms, the Temporal Dead Zone (TDZ), and production naming conventions.Beginner 25 min Level 1 — BeginnerData TypesMaster JavaScript data types: the 7 primitive types (String, Number, BigInt, Boolean, Undefined, Null, Symbol) vs Reference Objects, memory allocation, typeof operator, and instanceof checks.Beginner 30 min Level 1 — BeginnerOperatorsMaster JavaScript operators: arithmetic, assignment, comparison, strict vs loose equality, logical operators, nullish coalescing, optional chaining, ternary expressions, bitwise operators, delete, and precedence rules.Beginner 30 min Level 1 — BeginnerControl FlowMaster JavaScript control flow structures: conditional branching (if, else, else if, switch), iteration loops (for, while, do...while), jump statements (break, continue), and nested logic.Beginner 25 min Level 1 — BeginnerFunctionsMaster JavaScript functions: declarations vs expressions, arrow functions, parameters, arguments, return values, default and rest parameters, spread syntax, callbacks, higher-order functions, and pure functions.Beginner 35 min Level 1 — BeginnerStringsMaster JavaScript string manipulation: indexing, slicing, template literals, length property, searching (includes, startsWith, endsWith), trimming, casing, substring extraction, and regex replacement.Beginner 30 min Level 1 — BeginnerArraysMaster JavaScript arrays: creation, indexing, mutation methods (push, pop, shift, unshift, splice), non-mutating methods (slice, concat, join), searching (includes, indexOf), and memory characteristics.Beginner 30 min Level 1 — BeginnerArray MethodsMaster higher-order array methods in JavaScript: forEach, map, filter, find, findIndex, some, every, reduce, sort, reverse, flat, and flatMap for declarative data processing.Beginner 35 min Level 1 — BeginnerObjectsMaster JavaScript objects: object literals, properties, methods, nested objects, property access, computed property keys, object destructuring, spread operations, Object.keys, Object.values, Object.entries, and Object.assign.Beginner 35 min Level 1 — BeginnerThe DOMMaster the Document Object Model (DOM) in JavaScript: element selection, DOM querying, node creation, removal, innerText vs textContent vs innerHTML, attribute and class manipulation, inline styles, and tree traversal.Beginner 40 min Level 1 — BeginnerEventsMaster JavaScript events: addEventListener, mouse and keyboard events (click, submit, input, change, keydown, keyup), the Event object, preventDefault, stopPropagation, event bubbling, capturing phases, and event delegation patterns.Beginner 40 min Level 1 — BeginnerJSON & StorageMaster JSON and client-side data persistence: JSON syntax, serialization (JSON.stringify), deserialization (JSON.parse), localStorage, sessionStorage, storage limits, and Cookies basics.Beginner 30 min Level 1 — BeginnerBeginner ProjectsBuild 9 complete, practical, vanilla JavaScript beginner projects: Calculator, Todo App, Counter, Quiz App, Stopwatch, Weather App, Expense Tracker, Shopping Cart, and Image Gallery.Beginner 50 min Level 1 — BeginnerScope & ExecutionDeep dive into JavaScript execution: execution contexts, call stack, lexical environments, scope chain, variable hoisting, closures, and garbage collection mechanisms.Intermediate 35 min Level 2 — IntermediateThe this KeywordMaster the JavaScript this keyword: global context, method invocation, constructor calls, explicit binding (call, apply, bind), lexical this in arrow functions, and class contexts.Intermediate 35 min Level 2 — IntermediatePrototypes & ObjectsMaster JavaScript prototypes: prototype chain, Object.create, constructor functions, prototype methods, property descriptors, getters/setters, defineProperty, Object.freeze, and Object.seal.Intermediate 35 min Level 2 — IntermediateClasses & OOPMaster Object-Oriented Programming in modern JavaScript: ES6 classes, constructors, instance vs static methods, private fields (#), getters, setters, inheritance (extends, super), polymorphism, and composition vs inheritance.Intermediate 40 min Level 2 — IntermediateAdvanced FunctionsMaster advanced JavaScript function patterns: closures, higher-order functions, currying, partial application, function composition (pipe and compose), memoization caching, IIFEs, recursion, and factory functions.Intermediate 35 min Level 2 — IntermediateModulesMaster JavaScript modularity: ES Modules (ESM), import and export syntax, default vs named exports, dynamic imports (import()), CommonJS (CJS), ESM vs CJS interoperability, module resolution algorithms, and resolving circular dependencies.Intermediate 30 min Level 2 — IntermediateAsynchronous JavaScriptMaster asynchronous JavaScript: synchronous vs asynchronous execution, callbacks, callback hell, Promises, Promise states, .then/.catch/.finally, async/await, error handling, promise chaining, and Promise combinators (all, allSettled, race, any).Intermediate 45 min Level 2 — IntermediateThe Event LoopMaster the JavaScript Event Loop architecture: Call Stack, Memory Heap, Task Queue (Macrotasks), Microtask Queue, rendering cycles, setTimeout, setInterval, queueMicrotask, and requestAnimationFrame.Intermediate 40 min Level 2 — IntermediateFetch & APIsMaster client-side network communication: Fetch API, HTTP methods (GET, POST, PUT, PATCH, DELETE), headers, request payloads, response parsing, HTTP error handling, request cancellation with AbortController, and API authentication.Intermediate 40 min Level 2 — IntermediateError HandlingMaster robust JavaScript error handling: try/catch/finally blocks, throw statements, built-in error types (TypeError, ReferenceError, SyntaxError), custom error subclasses, asynchronous error handling, and global error boundaries.Intermediate 30 min Level 2 — IntermediateRegular ExpressionsMaster JavaScript Regular Expressions (RegExp): syntax, character classes, quantifiers, capturing and named groups, lookahead and lookbehind assertions, regex flags, and string methods (test, match, matchAll, replace).Intermediate 35 min Level 2 — IntermediateBrowser APIsMaster essential modern Web Browser APIs: URL, History API, Clipboard API, Geolocation, Notifications, File API, Drag & Drop, IntersectionObserver, ResizeObserver, MutationObserver, and Web/Service Workers.Intermediate 45 min Level 2 — IntermediateTestingMaster JavaScript testing strategies: Unit testing, Vitest, Jest, assertions, test suites, mocking, spies, fixtures, component testing, integration testing, and End-to-End (E2E) testing with Playwright and Cypress.Intermediate 40 min Level 2 — IntermediateToolingMaster the modern JavaScript tooling ecosystem: package managers (npm, pnpm, Yarn), package.json, lockfiles, semantic versioning, npm scripts, ESLint, Prettier, Vite, Babel, SWC, and modern bundlers.Intermediate 35 min Level 2 — IntermediateIntermediate ProjectsBuild 8 complete, production-grade intermediate JavaScript projects: REST API Client, E-Commerce Frontend, Auth Application, Admin Dashboard, Real-Time Chat, Kanban Board, Movie Application, and Advanced Expense Tracker.Intermediate 55 min Level 2 — IntermediateJavaScript Engine InternalsDeep dive into JavaScript engine internals: V8 architecture, lexical parsing, AST construction, Ignition bytecode interpreter, TurboFan optimizing compiler, JIT optimization, deoptimization (deopt bailouts), hidden classes (Shapes), inline caches (ICs), and generational garbage collection.Advanced 45 min Level 3 — AdvancedMemory ManagementMaster JavaScript memory management: Stack vs Heap allocation, Generational Garbage Collection (Scavenger / Minor GC vs Mark-Sweep-Compact / Major GC), memory leak detection, detached DOM nodes, WeakMap, WeakSet, WeakRef, and FinalizationRegistry.Advanced 45 min Level 3 — AdvancedAdvanced Async ProgrammingMaster advanced asynchronous JavaScript: Event loop scheduling internals, Async Iterators (Symbol.asyncIterator), Async Generators (for await...of), asynchronous queues, concurrency limiters, worker pools, cancellation tokens, exponential backoff retries, and race-condition prevention.Advanced 45 min Level 3 — AdvancedAdvanced Data StructuresMaster advanced data structures in JavaScript: Stack, Queue, Deque, Singly and Doubly Linked Lists, Hash Table with collision handling, Set, Map, Binary Search Tree (BST), Min/Max Heap, Graph, Trie (Prefix Tree), and LRU Cache.Advanced 45 min Level 3 — AdvancedAlgorithmsMaster essential algorithms in JavaScript: Big-O analysis (Time & Space complexity), Binary Search, Sorting (Merge Sort, Quick Sort), Dynamic Programming, Greedy approaches, Graph traversals (BFS, DFS), Two Pointers, and Sliding Window.Advanced 45 min Level 3 — AdvancedAdvanced Browser ArchitectureDeep dive into modern browser architecture: Multi-process model (Browser, Renderer, GPU, Network), Main Thread, DOM and CSSOM construction, Render Tree, Layout (Reflow), Paint (Repaint), Composite, Rasterization, and the 60fps rendering pipeline.Advanced 45 min Level 3 — AdvancedWeb PerformanceMaster web performance engineering: Core Web Vitals (LCP, INP, CLS, FCP, TTFB), Critical Rendering Path optimization, code splitting, tree shaking, asset preloading/prefetching, Long Task elimination, list virtualization, and performance budgets.Advanced 45 min Level 3 — AdvancedAdvanced Web APIsMaster advanced browser APIs: Web Workers, Shared Workers, Service Workers, Cache API, IndexedDB storage, WebSockets, WebRTC peer-to-peer data channels, Web Streams, Web Crypto API, WebAssembly (Wasm), BroadcastChannel, and Push API.Advanced 45 min Level 3 — AdvancedSecurityMaster frontend and JavaScript security: Cross-Site Scripting (XSS, DOM XSS), Cross-Site Request Forgery (CSRF), Cross-Origin Resource Sharing (CORS), Content Security Policy (CSP), Trusted Types, Same-Origin Policy, Prototype Pollution, and secure auth.Advanced 45 min Level 3 — AdvancedAdvanced ArchitectureMaster enterprise frontend architecture: Design patterns (Observer, Factory, Singleton, Strategy), SOLID principles, Dependency Injection (DI), Event-Driven Architecture, State Machines (XState), Micro-Frontends, and Design Systems.Advanced 45 min Level 3 — AdvancedFramework InternalsDeep dive into modern frontend framework internals: React (Fiber architecture, Reconciliation, Concurrent Mode, Suspense, RSCs, Hydration), Vue (Proxy Reactivity, Virtual DOM diffing, Compiler, Scheduler), and Svelte (Runes, Compile-time reactivity).Advanced 50 min Level 3 — AdvancedBuild SystemsMaster advanced JavaScript build systems: Vite, Webpack internals, Rollup, esbuild, SWC, Babel, Tree Shaking algorithms, granular Code Splitting, bundle analysis, high-fidelity Source Maps, caching strategies, and Module Federation.Advanced 40 min Level 3 — AdvancedProduction EngineeringMaster enterprise frontend production engineering: CI/CD automation with GitHub Actions, type checking, linting, security audits, Docker containerization, CDN edge distribution, environment/secrets management, feature flags, canary releases, and zero-downtime rollbacks.Advanced 45 min Level 3 — AdvancedObservabilityMaster frontend observability and production telemetry: Error tracking (Sentry), Source Map de-minification, Real User Monitoring (RUM), performance telemetry (Web Vitals), structured logging, custom business metrics, OpenTelemetry distributed tracing, and production debugging.Advanced 40 min Level 3 — AdvancedAdvanced TypeScriptMaster advanced TypeScript type-level programming: Type Inference, Generics with constraints, Conditional Types (T extends U ? X : Y), Mapped Types, Template Literal Types, Utility Types, Type Guards, Type Predicates (is), the infer keyword, and type architecture.Advanced 45 min Level 3 — AdvancedAdvanced ProjectsBuild 11 enterprise-grade, advanced JavaScript applications: Production-Grade SPA, Full-Stack SaaS, Enterprise Dashboard, Real-Time Collaboration Canvas, Offline-First PWA, Design System, Component Library, JS Utility Library, State Management Store, Typed API Client, and Browser-Based IDE.Advanced 60 min Level 3 — Advanced