javascript - 数组分组问题？

Question

我有一个数组，数组格式如下：

  [    {      id: 1,      name: 1,      msg: {        masterId: 1,        stackId: 2      }    },    {      id: 2,      name: 2,      msg: {        masterId: 1,        stackId: 2      }    },    {      id: 3,      name: 3,      msg: {        masterId: 3,        stackId: 3      }    },    {      id: 4,      name: 4    }  ]

想要根据msg中的masterId和stackId进行分组，masterId标识数据属于父元素，如果masterId和id相同，说明该元素为父元素，stackId标识这个设备属于一个组，最后想得到的格式如下

[  {      id: 1,      name: 1,      msg: {        masterId: 1,        stackId: 2      },      children: [      {          id: 2,          name: 2,          msg: {            masterId: 1,            stackId: 2          }        }      ]    },    {      id: 3,      name: 3,      msg: {        masterId: 3,        stackId: 3      }    },    {      id: 4,      name: 4    }]

请问该怎么做？

Answer 1

时间复杂度 O(n)，示例如下：

function func(array) {  const result = new Map();  for (const { id, name, msg } of array) {    if (msg && msg.masterId === id) {      result.set(id, { id, name, msg, children: [] });    } else if (msg && result.has(msg.masterId)) {      result.get(msg.masterId).children.push({ id, name, msg });    } else {      result.set(id, { id, name, msg });    }  }  return Array.from(result.values());}

Answer 2

let arr = [  {    id: 1,    name: 1,    msg: {      masterId: 1,      stackId: 2    }  },  {    id: 2,    name: 2,    msg: {      masterId: 1,      stackId: 2    }  },  {    id: 3,    name: 3,    msg: {      masterId: 3,      stackId: 3    }  },  {    id: 4,    name: 4  }];let result = arr.reduce((acc, cur) => {   let parent = acc.find(item => item.id === cur.msg?.masterId);  if (parent) {    if (!parent.children) {      parent.children = [];    }    parent.children.push(cur);  } else {    acc.push(cur);  }  return acc;}, []);console.log(result);