TypeScript

TypeScript

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Section 1: Getting Started

6Lessons ·
- 1: Why TypeScript: Static Typing Benefits
  
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- 2: Setting Up the TypeScript Compiler
  
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- 3: Configuring tsconfig.json
  
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- 4: Compiling TypeScript to JavaScript
  
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- 5: TypeScript in VS Code
  
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- 6: Understanding Structural Typing
  
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Section 2: Basic Types

8Lessons ·
- 7: Primitive Types and Type Annotations
  
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- 8: Arrays and Tuples
  
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- 9: Enums and Const Enums
  
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- 10: Type Inference
  
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- 11: The any, unknown, and never Types
  
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- 12: Type Aliases
  
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- 13: Object Types
  
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- 14: Practice Exercise: Typing a Simple Data Model
  
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Section 3: Functions and Objects

10Lessons ·
- 15: Typing Function Parameters and Returns
  
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- 16: Optional and Default Parameters
  
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- 17: Function Overloads
  
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- 18: Interfaces
  
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- 19: Interfaces vs Type Aliases
  
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- 20: Extending Interfaces
  
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- 21: Readonly Properties
  
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- 22: Index Signatures
  
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- 23: Optional Properties
  
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- 24: Practice Exercise: Typing a REST API Response Shape
  
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Section 4: Advanced Types

14Lessons ·
- 25: Union and Intersection Types
  
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- 26: Literal Types
  
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- 27: Type Narrowing and Type Guards
  
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- 28: Discriminated Unions
  
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- 29: Mapped Types
  
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- 30: Conditional Types
  
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- 31: Infer Keyword in Conditional Types
  
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- 32: Template Literal Types
  
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- 33: Utility Types: Partial, Pick, Omit, Record
  
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- 34: Utility Types: Required, Readonly, Exclude, Extract
  
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- 35: Utility Types: ReturnType and Parameters
  
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- 36: Recursive Conditional Types
  
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- 37: Distributive Conditional Types
  
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- 38: Practice Exercise: Building a Deep Partial Utility Type
  
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Section 5: Object-Oriented TypeScript

8Lessons ·
- 39: Classes and Access Modifiers
  
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- 40: Abstract Classes and Interfaces
  
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- 41: Generics in Classes and Functions
  
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- 42: Generic Constraints
  
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- 43: Decorators
  
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- 44: Parameter Properties in Constructors
  
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- 45: Static Members in Classes
  
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- 46: Practice Exercise: Building a Generic Repository Class
  
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Section 6: Working with Modules

6Lessons ·
- 47: Modules and Namespaces
  
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- 48: Declaration Files (.d.ts)
  
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- 49: Typing Third-Party JavaScript Libraries
  
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- 50: Ambient Declarations
  
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- 51: Module Resolution Strategies
  
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- 52: Publishing a Typed npm Package
  
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Section 7: Tooling and Practice

7Lessons ·
- 53: Strict Mode and Compiler Flags
  
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- 54: Integrating TypeScript with ESLint
  
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- 55: Migrating a JavaScript Project to TypeScript
  
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- 56: Debugging TypeScript with Source Maps
  
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- 57: Type-Checking Only Builds
  
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- 58: Project References for Monorepos
  
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- 59: Path Aliases and Module Resolution
  
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Section 8: Type-Level Programming

5Lessons ·
- 60: Building a Type-Safe Event Emitter
  
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- 61: Branded and Nominal Types in TypeScript
  
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- 62: Variadic Tuple Types
  
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- 63: Key Remapping in Mapped Types
  
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- 64: Practice Exercise: Building a Type-Safe Query Builder
  
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Section 9: TypeScript with Backends

4Lessons ·
- 65: Typing Node.js APIs and Express Handlers
  
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- 66: Typing GraphQL Schemas and Resolvers
  
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- 67: Configuring TypeScript for Monorepos with Turborepo or Nx
  
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- 68: Typing tRPC-Style End-to-End APIs
  
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Section 10: Testing Typed Code

3Lessons ·
- 69: Type Testing with tsd or expect-type
  
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- 70: Unit Testing TypeScript with Jest and ts-jest
  
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- 71: Mocking Typed Dependencies
  
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Section 11: Data Validation with Types

4Lessons ·
- 72: Runtime Validation with Zod
  
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- 73: Runtime Validation with io-ts
  
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- 74: Bridging Compile-Time Types and Runtime Validation
  
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- 75: Runtime Validation with Valibot
  
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Section 12: Practical Projects

8Lessons ·
- 76: Building a Typed CLI Tool
  
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- 77: Building a Type-Safe API Client
  
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- 78: Converting a Small JS Library to TypeScript
  
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- 79: Building a Typed Form Validation Library
  
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- 80: Building a Type-Safe State Management Store
  
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- 81: Building a Typed Event-Driven Task Queue
  
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- 82: Building a Typed In-Memory Cache with Generics
  
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- 83: Building a Typed Plugin System
  
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Section 13: Compiler Internals

6Lessons ·
- 84: How the TypeScript Compiler Works: AST and Type Checker
  
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- 85: Writing a Simple TypeScript Transformer
  
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- 86: Understanding Declaration Emit
  
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- 87: Language Service API Basics
  
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- 88: Type Checking Performance Profiling
  
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- 89: Common Causes of Slow Type Checking
  
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Section 14: Configuration Deep Dive

5Lessons ·
- 90: Understanding strict, strictNullChecks, and noImplicitAny
  
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- 91: Target and Module Settings Explained
  
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- 92: Path Mapping and baseUrl
  
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- 93: Skip Lib Check and Build Performance Flags
  
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- 94: Composite Projects and Incremental Builds
  
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Section 15: Enums, Symbols, and Special Types

5Lessons ·
- 95: String Enums vs Numeric Enums
  
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- 96: Const Assertions with as const
  
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- 97: The satisfies Operator
  
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- 98: Using Symbols with TypeScript
  
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- 99: Typing Iterators and Iterables
  
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Section 16: Working with Async Code

4Lessons ·
- 100: Typing Promises and Async Functions
  
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- 101: Typing Async Generators
  
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- 102: Handling Errors in Typed Async Code
  
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- 103: Typing Event-Based APIs
  
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Section 17: TypeScript and the DOM

4Lessons ·
- 104: Typing DOM Elements and Events
  
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- 105: Using lib.dom.d.ts Effectively
  
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- 106: Typing Custom DOM Events
  
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- 107: Practice Exercise: Typing a Vanilla TS DOM Widget
  
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Section 18: Advanced Generics Practice

5Lessons ·
- 108: Generic Defaults
  
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- 109: Constraining Generics with keyof
  
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- 110: Higher-Order Type Functions
  
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- 111: Practice Exercise: Building a Type-Safe Redux-Like Store
  
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- 112: Practice Exercise: Building a Type-Safe Router
  
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Section 19: Working with Third-Party Types

4Lessons ·
- 113: Finding and Installing @types Packages
  
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- 114: Writing Your Own .d.ts for an Untyped Library
  
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- 115: Module Augmentation
  
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- 116: Global Type Declarations
  
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Section 20: Monorepo and Large-Scale Practices

5Lessons ·
- 117: Structuring a Large TypeScript Codebase
  
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- 118: Shared Type Packages Across a Monorepo
  
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- 119: Enforcing Type Boundaries Between Modules
  
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- 120: Versioning Public Type Definitions
  
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- 121: Build Caching Strategies for TypeScript Monorepos
  
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Section 21: Common Pitfalls and Best Practices

8Lessons ·
- 122: Avoiding Overuse of any
  
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- 123: When to Use unknown Instead of any
  
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- 124: Common Type Assertion Mistakes
  
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- 125: Writing Types That Match Real Runtime Shapes
  
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- 126: Balancing Type Safety and Developer Ergonomics
  
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- 127: Avoiding Type Assertion Overuse
  
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- 128: Handling Third-Party Libraries Without Types
  
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- 129: Structuring Types for Long-Term Maintainability
  
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Section 22: Interview Practice

4Lessons ·
- 130: Common TypeScript Interview Questions on Generics
  
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- 131: Common TypeScript Interview Questions on Advanced Types
  
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- 132: Common TypeScript Interview Questions on Structural Typing
  
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- 133: Whiteboard Practice: Designing Types for a Real API
  
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Section 23: Handbook: Narrowing In Depth

8Lessons ·
- 134: typeof Type Guards
  
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- 135: Truthiness Narrowing
  
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- 136: Equality Narrowing
  
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- 137: The in Operator Narrowing
  
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- 138: instanceof Narrowing
  
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- 139: Assignment-Based Narrowing
  
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- 140: User-Defined Type Guard Functions
  
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- 141: The never Type and Exhaustiveness Checking
  
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Section 24: Handbook: Object Types In Depth

5Lessons ·
- 142: Optional Properties Revisited
  
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- 143: Readonly Array Types
  
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- 144: Tuple Types with Optional and Rest Elements
  
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- 145: Excess Property Checks
  
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- 146: Extending Types with Intersections
  
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Section 25: Handbook: Classes In Depth

8Lessons ·
- 147: Class Implements Clauses
  
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- 148: Member Visibility: public, private, protected
  
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- 149: The override Keyword
  
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- 150: Static Members and Static Blocks
  
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- 151: Generic Classes
  
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- 152: this Types and this-Based Type Guards
  
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- 153: Parameter Properties Revisited
  
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- 154: Abstract Construct Signatures
  
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Section 26: Handbook: Modules In Depth

5Lessons ·
- 155: How TypeScript Models JavaScript Modules
  
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- 156: ES Module Syntax in TypeScript
  
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- 157: CommonJS Interop
  
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- 158: Module Resolution: Node vs Bundler vs Classic
  
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- 159: Non-Modules and Script Files
  
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Section 27: Handbook: Declaration Files In Depth

4Lessons ·
- 160: Structure of .d.ts Files
  
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- 161: Publishing Type Definitions with a Package
  
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- 162: DefinitelyTyped and @types Packages
  
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- 163: Library Structures: Global, Modular, UMD
  
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Section 28: JSX and Namespaces

4Lessons ·
- 164: TypeScript and JSX Configuration
  
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- 165: Typing JSX Elements
  
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- 166: Namespaces vs Modules
  
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- 167: When to Still Use Namespaces
  
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Section 29: Compiler Configuration Reference

4Lessons ·
- 168: The tsconfig.json Reference In Depth
  
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- 169: Project References for Large Codebases
  
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- 170: Incremental Compilation Flags
  
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- 171: Module and Target Interactions
  
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Section 30: More Practice Exercises

3Lessons ·
- 172: Practice Exercise: Building a Type-Safe Form Builder
  
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- 173: Practice Exercise: Building a Typed Command Bus
  
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- 174: Practice Exercise: Modeling a State Machine with Discriminated Unions
  
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Section 31: Handbook: Everyday Types Deep Dive

7Lessons ·
- 175: The Array Type Syntax T[] vs Array<T>
  
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- 176: The object Type
  
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- 177: Type Aliases vs Interfaces Revisited
  
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- 178: Type Assertions and Non-Null Assertions
  
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- 179: Literal Inference and const Contexts
  
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- 180: The unique symbol Type
  
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- 181: BigInt Support in TypeScript
  
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Section 32: Utility Types Full Reference

11Lessons ·
- 182: Awaited<Type>
  
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- 183: Partial<Type> and Required<Type> Revisited
  
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- 184: Record<Keys, Type> In Depth
  
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- 185: Pick<Type, Keys> and Omit<Type, Keys> Revisited
  
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- 186: Exclude<Type, ExcludedUnion> and Extract<Type, Union>
  
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- 187: NonNullable<Type>
  
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- 188: Parameters<Type> and ConstructorParameters<Type>
  
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- 189: InstanceType<Type>
  
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- 190: ThisParameterType and OmitThisParameter
  
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- 191: ThisType<Type>
  
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- 192: Uppercase, Lowercase, Capitalize, Uncapitalize
  
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Section 33: Decorators Reference

8Lessons ·
- 193: Class Decorators
  
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- 194: Method Decorators
  
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- 195: Accessor Decorators
  
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- 196: Property Decorators
  
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- 197: Parameter Decorators
  
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- 198: Decorator Factories
  
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- 199: Decorator Composition Order
  
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- 200: Metadata Reflection with Decorators
  
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Section 34: Mixins and Advanced OOP Patterns

3Lessons ·
- 201: Mixin Classes Explained
  
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- 202: Constrained Mixins
  
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- 203: Alternative Patterns to Mixins
  
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Section 35: Iterators and Generators Typing

3Lessons ·
- 204: Typing Custom Iterable Classes
  
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- 205: Typing Generator Functions
  
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- 206: Typing Async Iterators
  
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Section 36: More Type-Level Programming Practice

6Lessons ·
- 207: Practice Exercise: Building a Type-Safe Path Getter (Deep Get)
  
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- 208: Practice Exercise: Building a JSON Schema to Type Mapper
  
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- 209: Practice Exercise: Building a Type-Safe Environment Variable Loader
  
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- 210: Practice Exercise: Building a Fluent Builder Pattern with Types
  
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- 211: Practice Exercise: Building a Type-Safe Router with Path Params
  
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- 212: Practice Exercise: Building a Type-Safe Reducer
  
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Section 37: TypeScript Ecosystem Tools

4Lessons ·
- 213: ts-node for Running TypeScript Directly
  
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- 214: Babel vs tsc for Transpilation
  
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- 215: esbuild and swc for Fast Compilation
  
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- 216: API Extractor for Public API Surfaces
  
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Section 38: TypeScript with Testing Frameworks

3Lessons ·
- 217: Configuring Vitest with TypeScript
  
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- 218: Type-Safe Mocking Patterns
  
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- 219: Testing Generic Functions
  
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Section 39: TypeScript for Library Authors

4Lessons ·
- 220: Designing a Good Public API Surface
  
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- 221: Versioning Type Definitions with SemVer
  
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- 222: Handling Breaking Type Changes
  
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- 223: Dual CJS/ESM Package Publishing with Types
  
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Section 40: More Interview Practice

3Lessons ·
- 224: Whiteboard Practice: Implementing DeepPartial Manually
  
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- 225: Whiteboard Practice: Implementing a Type-Safe Curry Function
  
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- 226: Common Interview Questions on Type Inference
  
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Section 41: Handbook: Functions In Depth

5Lessons ·
- 227: Call Signatures and Construct Signatures
  
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- 228: Function Overload Resolution Order
  
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- 229: Specifying void as a Return Type
  
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- 230: Rest Parameters and Rest Arguments Typing
  
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- 231: Parameter Destructuring with Types
  
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Section 42: Handbook: Type Manipulation Deep Dive

5Lessons ·
- 232: Generic Constraints with extends Revisited
  
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- 233: Using Type Parameters in Generic Constraints
  
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- 234: Optional Type Parameters with Defaults
  
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- 235: Conditional Types with Multiple Branches
  
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- 236: Mapped Type Modifiers: +/- readonly and +/- optional
  
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Section 43: More Real-World Patterns

8Lessons ·
- 237: Typing a Middleware Chain
  
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- 238: Typing an Event Bus with Overloaded Emit
  
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- 239: Typing a Plugin Registry
  
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- 240: Typing Feature Flags Safely
  
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- 241: Modeling Permissions with Literal Union Types
  
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- 242: Typing a Retry-with-Backoff Utility
  
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- 243: Typing a Cache Layer with Generics
  
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- 244: Typing a Multi-Step Wizard Form State
  
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Section 44: TypeScript Release Notes Highlights

3Lessons ·
- 245: What's New Across Recent TypeScript Versions
  
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- 246: Understanding Breaking Changes Between Major Versions
  
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- 247: Migrating Between TypeScript Versions Safely
  
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Section 45: Final Practice and Review

3Lessons ·
- 248: Practice Exercise: Building a Complete Typed API Layer End to End
  
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- 249: Practice Exercise: Refactoring an any-Heavy Codebase to Strict Types
  
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- 250: Code Review Checklist for TypeScript Pull Requests
  
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