Got it — here’s your React useState Immutable Update Cheatsheet condensed into a single interview-friendly page: React useState Immutable Update Cheatsheet 1. Rule #1 — Immutability Never mutate the existing state object. Always return a new reference so React knows to re-render. 2. Shallow Updates (One-Level Objects) jsx コピーする 編集する const [user, setUser] = useState({ name: 'Alice', age: 25 }); setUser(prev => ({ ...prev, name: 'Bob' // update one property })); 3. Deep Updates (Nested Objects)...