Fundamental Type Guards - TypeScript Narrowing #2

Опубликовано: 14 Май 2026
на канале: Lucas Paganini

3,405

138

The second video in our TypeScript Narrowing series. Learn 6 fundamental type guards (and techniques) available for narrowing:
1. The typeof operator
2. The in operator
3. The instanceof operator
4. Equality narrowing
5. Truthiness narrowing
6. Control flow analysis

📚 Read the article: https://www.lucaspaganini.com/academy...
🚨 Subscribe to the newsletter: https://www.lucaspaganini.com/newsletter

📧 Email: [email protected]
🐦 Twitter:   / lucaspaganini
📸 Instagram:   / lucaspaganini

----------

CHAPTERS
0:00 Introduction
0:12 Our Goal
0:29 The typeof Operator Guard
1:27 The in Operator Guard
2:43 Equality Narrowing
3:36 Truthiness Narrowing
4:35 Control Flow Analysis
5:28 The instanceof Operator Guard
5:53 Type never
6:09 Conclusion

RELATED
1. 1min JS - Falsy and Truthy:    • Falsy and Truthy in JavaScript
2. Null vs Undefined in JavaScript - Explained Visually:    • Null vs Undefined in JavaScript - Explaine...
3. TypeScript Narrowing Part 1 - What is a Type Guard:    • What is a Type Guard - TypeScript Narrowin...

REFERENCES
1. TypeScript docs on narrowing: https://www.typescriptlang.org/docs/h...
2. TypeScript docs on the never type: https://www.typescriptlang.org/docs/h...
3. The instanceof operator on MDN: https://developer.mozilla.org/pt-BR/d...
4. The typeof operator on MDN: https://developer.mozilla.org/pt-BR/d...
5. The in operator on MDN: https://developer.mozilla.org/pt-BR/d...

#typescript #programming #webdevelopment