如何根据对象中的id对json对象进行分组答案

【问题标题】：how to Group json object based on id in the object如何根据对象中的id对json对象进行分组
【发布时间】：2021-12-22 00:28:16
【问题描述】：

我需要用count将普通对象分组为单个，如何根据对象中的id对对象进行分组，以及如何在结果中添加额外的带有count的键。

 var a =[
{"name":"test","id":101,"price":100},
{"name":"test","id":101,"price":100},
{"name":"test3","id":103,"price":10},
{"name":"test2","id":102,"price":12},
]

输出 =

             [
                {"name":"test","id":101,"price":100,"qty":2},
                {"name":"test3","id":103,"price":10,"qty":1},
                {"name":"test2","id":102,"price":12,"qty":1},
            ]

【问题讨论】：

已经在stackoverflow.com/questions/38575721/grouping-json-by-values回复

标签： javascript node.js nodes

【解决方案1】：

尝试以下方法（当然不是最快但有效；）：

let myarray = [
 {"name":"test","id":101,"price":100},
 {"name":"test","id":101,"price":100},
 {"name":"test3","id":103,"price":10},
 {"name":"test2","id":102,"price":12},
];

let groupedArray = myarray.reduce((acc, cur) => { 
  let foundIndex = acc.findIndex(a => a.id == cur.id); 
  if (foundIndex != -1){ 
     acc[foundIndex].qty += 1  
  } else {
    cur.qty = 1; acc.push(cur) 
  } 
  return acc;
}, []);

// groupedArray contains the grouped objects

【讨论】：

【解决方案2】：

const a =[
    {"name":"test","id":101,"price":100},
    {"name":"test","id":101,"price":100},
    {"name":"test3","id":103,"price":10},
    {"name":"test2","id":102,"price":12},
];

const output = a.reduce((acc, nv, i, arr) => {
    const item = acc.find(e => e.id === nv.id);
    if(item) return acc;
    acc.push({ ...nv, count: arr.filter(e => e.id === nv.id)?.length });
    return acc;
}, []);

【讨论】：