todo-list.tsx

  todoReducer(state, action) {
    switch (action.type) {
      case 'CREATE':
        state = [...state, action.payload];
        return state;
      case 'DELETE':
        state = state.filter((todo) => {
          return todo.id !== action.payload.id;
        });
        return state;
      case 'UPDATE':
        const todos = state.concat([]);

        let todoToUpdate = todos.filter((todo) => {
          return todo.id === action.payload.id;
        })[0];

        todoToUpdate.value = action.payload.value;

        state = todos;
        return state;
      default:
        return state;
    }