Getting Started
This handbook is a practical guide to understanding and fixing TypeScript error messages as quickly as possible.
Have you ever thought:
- “I see the error message, but I don’t know what’s actually wrong.”
- “I Googled it, but none of the answers quite match my situation.”
This guide is designed to help you move forward without guessing, and to build the confidence to debug TypeScript errors on your own.
What You’ll Learn from This Handbook
Section titled “What You’ll Learn from This Handbook”With this handbook, you can:
- Understand common TypeScript error messages and what they really mean
- Learn the most frequent root causes behind each error
- See minimal, focused examples that reproduce the problem
- Apply practical fixes that work in real projects
- Recognize patterns so similar errors become easier over time
Each page focuses on one error, keeping explanations short, concrete, and beginner-friendly.
Who This Is For
Section titled “Who This Is For”This handbook is especially useful if you:
- Are new to TypeScript (Of course, those who want to know about errors too)
- Recently enabled
strictorstrictNullChecks - Can read basic TypeScript but struggle to interpret compiler errors
- Want a quick reference instead of long blog posts
No advanced type-level programming knowledge is required.
How to Use This Handbook
Section titled “How to Use This Handbook”You can read this handbook in two ways:
1. Search by Error Message or Code
Section titled “1. Search by Error Message or Code”If you see an error like:
TS2339: Property 'x' does not exist on type 'Y'Search for the error message or the error code (e.g. TS2339).
Each page explains:
- Why the error happens
- What TypeScript is trying to protect you from
- Multiple ways to fix it, with trade-offs
2. Browse by Category
Section titled “2. Browse by Category”Errors are grouped by categories such as:
- Type errors
- Null / undefined errors
- Function and argument errors
- Module and import errors
Browsing by category helps you spot recurring patterns in your mistakes.
TypeScript Versions
Section titled “TypeScript Versions”Examples in this handbook target TypeScript 5.x.
Error messages may vary slightly between versions, but the underlying concepts remain the same.
Would you like to contribute to TSBook?
Section titled “Would you like to contribute to TSBook?”This project is for all developers using TypeScript, so please feel free to submit pull requests. We look forward to your contributions.
A Note on Learning TypeScript
Section titled “A Note on Learning TypeScript”TypeScript errors are not just obstacles — they’re hints.
Each error message reflects a mismatch between what your code promises and what it actually does. Once you learn to read them calmly, TypeScript becomes less of an enemy and more of a safety net.
Let’s get started 🚀