App React State — Free App Development Tutorial
Learn App React State in App Development with a free, beginner-friendly tutorial, examples and practice for Indian students on Syllab.in.
TL;DR: Learn App React State in App Development with a free, beginner-friendly tutorial, examples and practice for Indian students on Syllab.in.
Written & reviewed by the Syllab.in Academic Team (CBSE/NCERT subject experts) · Updated
App React State in App Development
State is data that changes over time within a component, triggering a re-render when updated.
The useState hook returns a state value and a setter function: const [value, setValue] = useState(initial).
The useEffect hook runs side effects (data fetching, subscriptions) after render, with an optional dependency array.
Rules of Hooks: only call hooks at the top level, never inside loops or conditions, and only in React functions.
Lifting state up means moving shared state to the closest common ancestor so multiple child components can access it.
App React State — Syntax
// useState
const [count, setCount] = useState(0);
setCount(prev => prev + 1); // functional update
// useEffect
useEffect(() => {
document.title = \
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