Modules & Namespaces
Module Augmentation
Patch and extend existing module types from external npm packages.
Last Updated: July 29, 2026
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10 min read
Module augmentation allows adding new properties or methods to third-party library modules without editing vendor source files.
1. Introduction & Architecture
2. Deep Dive & Core Concepts
Using declare module 'module-name' extends existing interface declarations via declaration merging.
3. Basic Code Example
4. Advanced Production Patterns
5. Interactive Code Playground
console.log("Module augmentation allows safe type extensions for third-party libs.");6. Common Pitfalls & Edge Cases
Note: Module augmentation requires importing the target module before declaring module overrides.
7. Interview Q&A & Quizzes
Q: What is Module Augmentation?
A: A technique for adding type declarations to external modules using declaration merging.
8. Summary Comparison Table
| Purpose | Syntax |
|---|---|
| Extend Express Request | declare module 'express' { interface Request { ... } } |
declare module 'axios' { interface AxiosRequestConfig { ... } } |