Interview question

What is useReducer and when should you use it? useReducer क्या है और कब use करें?

Answer

// useReducer for complex state logic
const initialState = { count: 0 };

function reducer(state, action) {
  switch(action.type) {
    case 'INCREMENT':
      return { count: state.count + 1 };
    case 'DECREMENT':
      return { count: state.count - 1 };
    case 'RESET':
      return { count: 0 };
    default:
      return state;
  }
}

function Counter() {
  const [state, dispatch] = useReducer(reducer, initialState);
  
  return (
    <div>
      <p>Count: {state.count}</p>
      <button onClick={() => dispatch({ type: 'INCREMENT' })}>+</button>
      <button onClick={() => dispatch({ type: 'DECREMENT' })}>-</button>
      <button onClick={() => dispatch({ type: 'RESET' })}>Reset</button>
    </div>
  );
}

useReducer - complex state के लिए
const [state, dispatch] = useReducer(reducer, initialState);

Reducer function:
function reducer(state, action) {
  switch(action.type) {
    case 'ACTION':
      return newState;
  }
}

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