No Types? No Problem – Manually Add TypeScript Type Defs for a JS Library - (Step-by-Step Guide)
📦 *How to Create TypeScript Types for JavaScript Libraries Without Type Definitions*
What if the JavaScript library you want to use in your TypeScript project *has no published types and no @types support?* In this full step-by-step demo, I show you *exactly how to handle this situation* — from importing the CommonJS module to writing and testing your own `.d.ts` file.
If you're working with untyped libraries and getting frustrated, this is the video for you.
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⏱️ *Chapters / Time Markers*
00:00 Introduction to problem
00:33 Type definition files
01:04 Real world example of js lib without published types
01:39 Demo of issues when native commonjs lib is consumed and how to fix
03:24 Inspecting js lib code to infer types
05:28 Decide location for type definition files
05:30 Creating type definition file
06:39 Informing typescript about your custom type definitions
08:00 Testing type defintions with js lib
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🧰 *What You’ll Learn:*
How to import CommonJS libraries with no type definitions
What errors TypeScript throws — and how to fix them
How to explore JS code to infer accurate types
Where to place your custom type definitions (`.d.ts`)
How to update your `tsconfig.json` to include your types
How to safely use & test the typed library in your codebase
📚 This is part of the *Complete TypeScript Crash Course Playlist*
👈 *Previous: Practical TypeScript Topics – Async, Promises & DefinitelyTyped* → • TypeScript for Real Projects – Async Funct...
👉 *Next: Best Practices for TypeScript in Real Projects* → • 3 TypeScript Mistakes Beginners Make (and ...
💬 Struggling with a specific JS library? Drop a comment and I’ll help you figure out the typings.
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TypeScript Crash Course:
Single video: • TypeScript Tutorial 2025 – 90-Min Full Cou...
Playlist: • The Ultimate TypeScript Crash Course Playl...
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