TypeScript with React
Typing useState, useEffect, useRef
Type built-in React hooks for state, side-effects, DOM elements, and mutable timers.
Last Updated: July 29, 2026
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10 min read
React hooks infer types automatically for initial values or accept explicit generics (useState(null)).
1. Introduction & Architecture
2. Deep Dive & Core Concepts
DOM refs initialized with null return a read-only RefObject; mutable timer refs return MutableRefObject.
3. Basic Code Example
4. Advanced Production Patterns
5. Interactive Code Playground
console.log("React hooks typed with state and ref generics.");6. Common Pitfalls & Edge Cases
Warning: Always pass
null as initial value to useRef(null) when attaching to DOM elements!7. Interview Q&A & Quizzes
Q: How do you type a DOM element ref in React?
A: useRef(null). Passing null creates an immutable RefObject managed by React.
8. Summary Comparison Table
| Hook | Generics Usage |
|---|---|
useState() | Union types for state initialized as null |
useRef(null) | DOM element reference |