TypeScript مع React: الأنواع العامة لـ FC وhooks

كتابة أنواع المكونات

// Recommended:
interface ButtonProps {
  label: string;
  onClick: () => void;
  disabled?: boolean;
}

function Button({ label, onClick, disabled }: ButtonProps) {
  return <button onClick={onClick} disabled={disabled}>{label}</button>;
}

كتابة نوع children

interface CardProps {
  title: string;
  children: React.ReactNode;
}

function Card({ title, children }: CardProps) {
  return (
    <div className="card">
      <h2>{title}</h2>
      {children}
    </div>
  );
}

كتابة نوع useState

const [count, setCount] = useState(0);              // number
const [name, setName] = useState('');                // string

const [user, setUser] = useState<User | null>(null); // explicit
const [items, setItems] = useState<Item[]>([]);      // explicit array type

كتابة نوع useRef

const inputRef = useRef<HTMLInputElement>(null);
const timerRef = useRef<number | null>(null);

useEffect(() => {
  inputRef.current?.focus();
  timerRef.current = window.setInterval(tick, 1000);
  return () => clearInterval(timerRef.current!);
}, []);

كتابة أنواع معالجات الأحداث

function Form() {
  function onSubmit(e: React.FormEvent<HTMLFormElement>) {
    e.preventDefault();
  }
  function onChange(e: React.ChangeEvent<HTMLInputElement>) {
    setValue(e.target.value);
  }
  function onClick(e: React.MouseEvent<HTMLButtonElement>) {
    /* ... */
  }
  return <form onSubmit={onSubmit}>...</form>;
}

المكونات العامة

interface ListProps<T> {
  items: T[];
  renderItem: (item: T) => React.ReactNode;
  keyOf: (item: T) => string | number;
}

function List<T>({ items, renderItem, keyOf }: ListProps<T>) {
  return <ul>{items.map(i => <li key={keyOf(i)}>{renderItem(i)}</li>)}</ul>;
}

<List<User>
  items={users}
  renderItem={u => u.name}
  keyOf={u => u.id}
/>

كتابة أنواع الخطافات المخصصة

function useToggle(initial = false): [boolean, () => void] {
  const [value, setValue] = useState(initial);
  const toggle = () => setValue(v => !v);
  return [value, toggle]; // tuple — annotation makes this stable
}

const [isOpen, toggle] = useToggle();

كتابة نوع Context

interface AuthContextValue {
  user: User | null;
  signIn: (email: string, pw: string) => Promise<void>;
  signOut: () => void;
}

const AuthContext = createContext<AuthContextValue | null>(null);

export function useAuth() {
  const ctx = useContext(AuthContext);
  if (!ctx) throw new Error('useAuth must be inside AuthProvider');
  return ctx;
}

كتابة نوع useReducer

type State = { count: number };
type Action =
  | { type: 'increment' }
  | { type: 'decrement' }
  | { type: 'set'; value: number };

function reducer(state: State, action: Action): State {
  switch (action.type) {
    case 'increment': return { count: state.count + 1 };
    case 'decrement': return { count: state.count - 1 };
    case 'set':       return { count: action.value };
  }
}

const [state, dispatch] = useReducer(reducer, { count: 0 });

تجنبوا React.FC

أداة ComponentPropsWithoutRef

type ButtonProps = React.ComponentPropsWithoutRef<'button'> & {
  variant?: 'primary' | 'secondary';
};

function Button({ variant = 'primary', ...rest }: ButtonProps) {
  return <button className={`btn ${variant}`} {...rest} />;
}

اختبار سريع

مراجعة: TypeScript + React