JavaScript Mastery in 90 Days
Days 1–15: Core Foundations (Non-Negotiable)
Day 1 – What JavaScript is & where it runs
Day 2 – JS Engine & Runtime basics
Day 3 – Variables (let, const)
Day 4 – Data Types & typeof
Day 5 – Type Coercion & Equality
Day 6 – Operators & Expressions
Day 7 – Conditionals (if / switch)
Day 8 – Loops (for, while)
Day 9 – Functions & Parameters
Day 10 – Scope (global, block, function)
Day 11 – Hoisting explained clearly
Day 12 – Execution Context
Day 13 – Call Stack basics
Day 14 – Memory & Garbage Collection
Day 15 – Write clean JS code
Days 16–30: Data Structures & Core JS
Day 16 – Arrays (real-world usage)
Day 17 – Array methods (map, filter, reduce)
Day 18 – Objects & key-value logic
Day 19 – Reference vs Value
Day 20 – this keyword (all cases)
Day 21 – bind, call, apply
Day 22 – Closures (power of functions)
Day 23 – Lexical Environment
Day 24 – Prototypes
Day 25 – Prototypal Inheritance
Day 26 – Classes (syntactic sugar)
Day 27 – OOP in JavaScript
Day 28 – Functional Programming basics
Day 29 – Pure functions & immutability
Day 30 – Mini Project (Logic-heavy)
Days 31–45: Asynchronous JavaScript
Day 31 – Sync vs Async JS
Day 32 – Web APIs
Day 33 – setTimeout & setInterval
Day 34 – Callbacks
Day 35 – Callback Hell
Day 36 – Promises (deep understanding)
Day 37 – Promise chaining
Day 38 – async / await
Day 39 – Error handling in async code
Day 40 – Event Loop (must-know)
Day 41 – Microtasks vs Macrotasks
Day 42 – Fetch API
Day 43 – Axios vs Fetch
Day 44 – Retry & timeout logic
Day 45 – Async mini project
Days 46–60: Browser & Advanced JS
Day 46 – DOM Tree & Rendering
Day 47 – DOM Selection & Manipulation
Day 48 – Events & Event Flow
Day 49 – Event Delegation
Day 50 – Forms & Validation
Day 51 – LocalStorage & SessionStorage
Day 52 – Cookies basics
Day 53 – Debouncing
Day 54 – Throttling
Day 55 – Shallow vs Deep Copy
Day 56 – Spread & Rest operators
Day 57 – Destructuring
Day 58 – Modules (import/export)
Day 59 – Bundlers basics
Day 60 – Browser performance tips
Days 61–75: Advanced Concepts (Interview Level)
Day 61 – JavaScript Internals revision
Day 62 – Memory leaks & prevention
Day 63 – Currying
Day 64 – Composition vs Inheritance
Day 65 – Design patterns (JS-focused)
Day 66 – Observer pattern
Day 67 – Singleton pattern
Day 68 – Factory pattern
Day 69 – Error boundaries (concept)
Day 70 – Custom utility functions
Day 71 – Polyfills
Day 72 – Write your own map/filter
Day 73 – Immutable data patterns
Day 74 – Functional vs OOP tradeoffs
Day 75 – Advanced problem solving
Days 76–90: Mastery & Real World
Day 76 – JS best practices
Day 77 – Code readability & refactoring
Day 78 – Time & Space Complexity
Day 79 – Testing basics
Day 80 – Debugging like a pro
Day 81 – Browser dev tools mastery
Day 82 – Security basics (XSS, CSRF)
Day 83 – JS performance optimization
Day 84 – Build reusable utilities
Day 85 – Real-world project planning
Day 86 – Project implementation
Day 87 – Edge cases handling
Day 88 – Refactor & optimize
Day 89 – Interview-level revision
Day 90 – You don’t “know JS” — you OWN it
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