扁平化数组转树，求最优方案

Question

我们看下题目：
const data = [

    {
        "_id": "2d44d6c26110d22203f5fbf95484b816",
        "comment_content": "测试评论",
        "article_id": "cd045e756102b0b600e6153e7dc3e678",
        "comment_author": {
            "name": "用户97.89556629736191",
            "email": "用户52.8973290551612@github.com"
        }
    },
    {
        "_id": "14139e126110d75503f2df4a0354e831",
        "comment_content": "第二条评论",
        "article_id": "cd045e756102b0b600e6153e7dc3e678",
        "comment_author": {
            "name": "用户27.064798298154493",
            "email": "用户97.70539438271202@github.com"
        }
    },
    {
        "_id": "cd045e7561121d9404c02e1a61856780",
        "comment_content": "大萨达",
        "article_id": "8937eaa96102b10200bc97bd4e2c6183",
        "comment_author": {
            "name": "用户45.88242116867542",
            "email": "用户36.95435829054714@github.com"
        }
    },
    {
        "_id": "14139e1261129806045420e93a9a9922",
        "comment_content": "二级评论",
        "reply_content": "二级评论",
        "pid": {
            "_id": "2d44d6c26110d22203f5fbf95484b816",
            "comment_content": "测试评论",
            "article_id": "cd045e756102b0b600e6153e7dc3e678",
            "comment_author": {
                "name": "用户97.89556629736191",
                "email": "用户52.8973290551612@github.com"
            }
        },
        "comment_author": {
            "name": "用户79.29663107058975",
            "email": "用户63.831949036364335@github.com"
        }
    }
]

输出结果
const data = [

    {
        "_id": "2d44d6c26110d22203f5fbf95484b816",
        "comment_content": "测试评论",
        "article_id": "cd045e756102b0b600e6153e7dc3e678",
        "comment_author": {
            "name": "用户97.89556629736191",
            "email": "用户52.8973290551612@github.com"
        },
                    children: [
                        {
                            "_id": "14139e1261129806045420e93a9a9922",
                            "comment_content": "二级评论",
                            "reply_content": "二级评论",
                            "pid": {
                                    "_id": "2d44d6c26110d22203f5fbf95484b816",
                                    "comment_content": "测试评论",
                                    "article_id": "cd045e756102b0b600e6153e7dc3e678",
                                    "comment_author": {
                                        "name": "用户97.89556629736191",
                                        "email": "用户52.8973290551612@github.com"
                                    }
                            },
                            "comment_author": {
                                    "name": "用户79.29663107058975",
                                    "email": "用户63.831949036364335@github.com"
                            }
                        }
                    ]
    },
    {
        "_id": "14139e126110d75503f2df4a0354e831",
        "comment_content": "第二条评论",
        "article_id": "cd045e756102b0b600e6153e7dc3e678",
        "comment_author": {
            "name": "用户27.064798298154493",
            "email": "用户97.70539438271202@github.com"
        },
                    children: []
    },
    {
        "_id": "cd045e7561121d9404c02e1a61856780",
        "comment_content": "大萨达",
        "article_id": "8937eaa96102b10200bc97bd4e2c6183",
        "comment_author": {
            "name": "用户45.88242116867542",
            "email": "用户36.95435829054714@github.com"
        },
                    children: []
    },
    
]

要求：
时间二十分钟，所有代码全部手写，不能用除了原生之外的第三方代码。
加强版：
1、树表联动。改动树或表其中一个数据，另一个数据也可以随之改变
最后
希望大佬们能给个最优方案，在评论里发出来，互相探讨（进去喝了三杯茶没写出来）

Answer 1

//数据

const data = [

    {
        "_id": "2d44d6c26110d22203f5fbf95484b816",
        "comment_content": "测试评论",
        "article_id": "cd045e756102b0b600e6153e7dc3e678",
        "comment_author": {
            "name": "用户97.89556629736191",
            "email": "用户52.8973290551612@github.com"
        }
    },
    {
        "_id": "14139e126110d75503f2df4a0354e831",
        "comment_content": "第二条评论",
        "article_id": "cd045e756102b0b600e6153e7dc3e678",
        "comment_author": {
            "name": "用户27.064798298154493",
            "email": "用户97.70539438271202@github.com"
        }
    },
    {
        "_id": "cd045e7561121d9404c02e1a61856780",
        "comment_content": "大萨达",
        "article_id": "8937eaa96102b10200bc97bd4e2c6183",
        "comment_author": {
            "name": "用户45.88242116867542",
            "email": "用户36.95435829054714@github.com"
        }
    },
    {
        "_id": "14139e1261129806045420e93a9a9922",
        "comment_content": "二级评论",
        "reply_content": "二级评论",
        "pid": {
            "_id": "2d44d6c26110d22203f5fbf95484b816",
            "comment_content": "测试评论",
            "article_id": "cd045e756102b0b600e6153e7dc3e678",
            "comment_author": {
                "name": "用户97.89556629736191",
                "email": "用户52.8973290551612@github.com"
            }
        },
        "comment_author": {
            "name": "用户79.29663107058975",
            "email": "用户63.831949036364335@github.com"
        }
    }
];

//方法

let res = data.reduce((acc,cur, idx, arr)=>(arr.forEach((item,index)=>(item?.pid?._id==cur._id && ((cur.children||=[]).push(item),arr.splice(index,1)))),acc.push(cur),acc),[])
console.log(JSON.stringify(res));

//结果

[
  {
    "_id": "2d44d6c26110d22203f5fbf95484b816",
    "comment_content": "测试评论",
    "article_id": "cd045e756102b0b600e6153e7dc3e678",
    "comment_author": {
      "name": "用户97.89556629736191",
      "email": "用户52.8973290551612@github.com"
    },
    "children": [
      {
        "_id": "14139e1261129806045420e93a9a9922",
        "comment_content": "二级评论",
        "reply_content": "二级评论",
        "pid": {
          "_id": "2d44d6c26110d22203f5fbf95484b816",
          "comment_content": "测试评论",
          "article_id": "cd045e756102b0b600e6153e7dc3e678",
          "comment_author": {
            "name": "用户97.89556629736191",
            "email": "用户52.8973290551612@github.com"
          }
        },
        "comment_author": {
          "name": "用户79.29663107058975",
          "email": "用户63.831949036364335@github.com"
        }
      }
    ]
  },
  {
    "_id": "14139e126110d75503f2df4a0354e831",
    "comment_content": "第二条评论",
    "article_id": "cd045e756102b0b600e6153e7dc3e678",
    "comment_author": {
      "name": "用户27.064798298154493",
      "email": "用户97.70539438271202@github.com"
    }
  },
  {
    "_id": "cd045e7561121d9404c02e1a61856780",
    "comment_content": "大萨达",
    "article_id": "8937eaa96102b10200bc97bd4e2c6183",
    "comment_author": {
      "name": "用户45.88242116867542",
      "email": "用户36.95435829054714@github.com"
    }
  }
]

加强版：
1、树表联动。改动树或表其中一个数据，另一个数据也可以随之改变

//方法
var syncObjValue=(a,b)=>Object.entries(a).forEach(([key, value])=>{
    Object.defineProperty(a, key, {
      get() { return value; },
      set(newValue) { value = newValue;(b[key]!=newValue && (b[key]=newValue)); }
    });
});

let res = data.reduce((acc,cur, idx, arr)=>(arr.forEach((item,index)=>(item?.pid?._id==cur._id && (syncObjValue(item),(cur.children||=[]).push(item),arr.splice(index,1)))),acc.push(cur),acc),[])
data[0]._id='55';
console.log(JSON.stringify(data),JSON.stringify(res));
res[0]._id='66';
console.log(JSON.stringify(data),JSON.stringify(res));

Answer 2

二级评论项塞入 pid 对应项的 children 里就行了。

const menuDict = data.reduce((iter, val) => {
    val.children = [];
    iter[val._id] = val;
    return iter;
}, {});


const result = data.reduce((iter, val) => {
    if (val.pid && menuDict[val.pid._id]) {
        menuDict[val.pid._id].children.push(val);
    } else {
        iter.push(val);
    }
    return iter;
}, []);

console.log(result);