根据数组对象列表对Javascript对象进行分组

问题描述

我正在尝试找到一种基于组array来转换此对象列表的方法。我发现最棘手的部分是遍历数组Array，如果有多个组，则将该对象应用于多个地方。

我还试图忽略任何不属于任何事物的组。我尝试使用reduce函数，但是无法通过组数组进行迭代。

  let cars = 
    [
      {
        "group":[],"name": "All Makes","code": ""
      },{
        "group":["Group A"],"name": "BMW","code": "X821"
      },{
        "group":["Group B"],"name": "Audi","code": "B216"
      },"name": "Ford","code": "P385"    
      },{
        "group":["Group B","Group C"],"name": "Mercedes","code": "H801"
      },{
        "group":["Group C"],"name": "Honda","code": "C213"
      }
    ]

要成为这个人

let cars = {
    "Group A": [
      {
        name: "BMW",code: "X821",}
    ],"Group B": [
      {
        name: "Audi",code: "B216"
      },{
        name: "Ford",code: "P385"
      },{
        name: "Mercedes",code: "H801"
      }
    ],"Group C":[
      {
        name: "Mercedes",code: "H801"
      },{
        name:"Honda",code: "C213"
      }
    ]
  };

我已经尝试使用reduce来完成此操作，但是如果分组在多个组中，则分组不会重复。

let result = cars.reduce(function(x,{group,name}){
  return Object.assign(x,{[group]:(x[group] || [] ).concat({group,name})})
},{});

任何有助于此目的的指针将不胜感激。

解决方法

您可以使用.reduce()遍历cars中的每个汽车对象。然后，对于给定汽车的每个group数组，您可以使用.forEach()将该组添加为累加器的键。如果已经在累加器中设置了组，则可以获取对象的分组数组，否则，可以创建新的数组[]。一旦有了数组，就可以使用.concat()将对象添加到数组中。由于我们在.forEach()数组上使用group，因此如果对象为空，它不会将对象添加到累积的对象中，因为.forEach()不会迭代一个空数组。 / p>

请参见以下示例：

const cars = [{ "group":[],"name": "All Makes","code": "" },{ "group":["Group A"],"name": "BMW","code": "X821" },{ "group":["Group B"],"name": "Audi","code": "B216" },"name": "Ford","code": "P385" },{ "group":["Group B","Group C"],"name": "Mercedes","code": "H801" },{ "group":["Group C"],"name": "Honda","code": "C213" } ];
          
const res = cars.reduce((acc,{group,...r}) => {
  group.forEach(key => {
    acc[key] = (acc[key] || []).concat({...r}); // copy r so it is a different reference for each grouped array
  });
  return acc;
},{});
console.log(res);

,

一些基本方法。 @尼克的好多了。

let cars = [{
    "group": [],"code": ""
  },{
    "group": ["Group A"],"code": "X821"
  },{
    "group": ["Group B"],"code": "B216"
  },"code": "P385"
  },{
    "group": ["Group B","code": "H801"
  },{
    "group": ["Group C"],"code": "C213"
  }
]
let newCars = {};
cars.forEach(o => {
  o.group.forEach(g => {
    if (!newCars[g])
      newCars[g] = [];
    newCars[g].push({
      name: o.name,code: o.code
    });
  });
});
console.log(newCars);