如何聚合以日期为键的对象 javascript

How to aggregate objects with dates as keys in javascript

我有一个对象,其键为以下格式的日期 "yyyy-mm-dd"(例如:2020-08-14) 每个键的值是一个对象数组,具有名称和值两个属性。

我需要找到一种方法来获取按 name 累计 N 天分组的密钥value 的总和。

这里有一个例子可以更好地理解,原始对象有 4 天的数据,其中一天有一个空数组:

{
  "2020-10-15":[
    {"name":"France","value":20},
    {"name":"United States","value":20},
    {"name":"Italy","value":5},
   ],
 "2020-10-16":[
    {"name":"Germany","value":10},
    {"name":"United States","value":5},
    {"name":"France","value":10}
   ],
  "2020-10-17":[],
   "2020-10-18":[
    {"name":"UK","value":10},
    {"name":"Italy","value":10},
   ]

 }

例如,如果我们希望按 4 天对这些数据进行分组,我们将得到以下结果:

[{"name": "France", "value": 30},
 {"name": "United States", "value": 25},
 {"name": "Italy", "value": 15},
 {"name": "Germany", "value": 10},
 {"name": "UK", "value": 10}]

这是 4 天内名称值相同的所有对象的总和。我完全不知道如何实现这一点,我知道可以使用 map 来迭代对象键并通过 moment js 进行一些处理,但我不知道如何实现这一点。

您可以使用 reduce, forEach and Object.keys 方法执行以下操作,

const value = {
  "2020-10-15":[
    {"name":"France","value":20},
    {"name":"United States","value":20},
    {"name":"Italy","value":5},
   ],
 "2020-10-16":[
    {"name":"Germany","value":10},
    {"name":"United States","value":5},
    {"name":"France","value":10}
   ],
  "2020-10-17":[],
   "2020-10-18":[
    {"name":"UK","value":10},
    {"name":"Italy","value":10},
   ]

 }

let res = Object.keys(value).reduce((prev, curr) => {
   value[curr].forEach(item => {
      const idx = prev.findIndex(pItem => pItem.name === item.name);
      if(idx > -1) {
         const newObj = {...prev[idx], value: prev[idx].value + item.value};
         prev[idx] = newObj;
         return ;
      }
      prev.push(item);
   })
   return prev;
}, []);
console.log(res);