javascript - 按相同的属性值对数组进行分组，遍历该数组

Question

我有以下数组:

var results = [
  { group: 1,
    department: 2,
    total: 10 },
  { group: 1,
    department: 2,
    total: 25 },
  { group: 1,
    department: 3, 
    total: 15 },
  { group: 1,
    department: 3,
    total: 5 },
  { group: 2,
    department: 4,
    total: 10},
  { group: 2,
    department: 4, 
    total: 50 }
]

我需要将数组排列成一个二维嵌套数组，其中子数组是第 1 组和第 2 组。子数组也应该是父数组，其子数组按部门排序，如下所示:

var results:[  
   {  
      group1:[  
         {  
            department2:[  
               {  
                  group:1,
                  department:2,
                  total:10
               },
               {  
                  group:1,
                  department:2,
                  total:25
               },
               {  
                  group:1,
                  department:3,
                  total:15
               }
            ]
         },
         {  
            department3:[  
               {  
                  group:1,
                  department:3,
                  total:5
               }
            ]
         }
      ]
   },
   {  
      group2:[  
         {  
            department4:[  
               {  
                  group:2,
                  department:4,
                  total:10
               },
               {  
                  group:2,
                  department:4,
                  total:50
               }
            ]
         }
      ]
   }
]

这是一个 React 组件，我需要将每个打印成一行，但在完成所有部门组后添加总计，然后在每个组后添加一个，然后在所有内容后添加总计。

也许我把它复杂化了，有更好的方法吗？

Answer 1

var results = [
  { group: 1,
    department: 2,
    total: 10 },
  { group: 1,
    department: 2,
    total: 25 },
  { group: 1,
    department: 3, 
    total: 15 },
  { group: 1,
    department: 3,
    total: 5 },
  { group: 2,
    department: 4,
    total: 10},
  { group: 2,
    department: 4, 
    total: 50 }
]

var nested_result = {}

results.forEach(obj => {
  if(nested_result[obj.group] === undefined) {
    nested_result[obj.group] = {};
  }
  if(nested_result[obj.group][obj.department] === undefined) {
    nested_result[obj.group][obj.department] = [];
  }
  nested_result[obj.group][obj.department].push(obj);
})

console.log(nested_result);