Object Arr.tsx

const board =
  draft.board[
    draft.board.findIndex(board => board.pk === action.meta.board_pk)
  ];
Object.assign(
  board.comment[
    board.comment.findIndex(comment => comment.pk === action.payload.pk)
  ],
  action.payload,
);

// first

// 위와 동일한 board

board.comment[
    board.comment.findIndex(comment => comment.pk === action.payload.pk)
  ] = {
    ...action.payload,
    ...board.comment[
    board.comment.findIndex(comment => comment.pk === action.payload.pk)
    ]
  }

// second

// 동일한 board

board.comment[
    board.comment.findIndex(comment => comment.pk === action.payload.pk)
  ] = {
    ...action.payload,
    나머지 모든 
  }

import produce from 'immer';


const state = {
  doNotTouchMe: false,
  boards: [
    {
      id: 1,
      comments: [],
    },
    {
      id: 2,
      comments: [],
    },
    {
      id: 3,
      comments: [
        {
          id: 1,
        },
        {
          id: 2,
        },
        {
          id: 3,
        },
        // ...
      ],
    },
  ]
}

const action = {
  type: 'LOAD_MORE_COMMENTS',
  payload: {
    board_id: 3,
    comment_id: 3,
    data: {
      text: 'lalalala'
    }
  }
}

const nextState = produce(state, draft => {
  const board = state.boards.find(board => board.id === action.payload.board_id);
  const comment = board.comments.find(comment => comment.id === action.payload.comment_id);
  Object.assign(comment, action.payload.data);
})

console.log(JSON.stringify(nextState, null, 2));