javascript - 如何在javascript中将对象数组转换为数组对象？

Question

我正在尝试使用 javascript 将对象数组转换为数组对象。

这是代码

const data = [{
  yearMonthKey: "201907",
  dayKey: "15",
  startDate: "2019-07-15 00:00:00+0900",
  title: "testProgrma"
},
             {
  yearMonthKey: "201907",
  dayKey: "15",
  startDate: "2019-07-15 00:00:00+0900",
  title: "testProgrma"
},
            {
  yearMonthKey: "201907",
  dayKey: "16",
  startDate: "2019-07-15 00:00:00+0900",
  title: "testProgrma12313"
},
            {
  yearMonthKey: "201908",
  dayKey: "15",
  startDate: "2019-07-15 00:00:00+0900",
  title: "testProgrma"
}]

let programs = {};

我想使用 programs 对象来制作一个对象，如下所示。

{
  201907: {
    15: [{
      yearMonthKey: "201907",
      dayKey: "15",
      startDate: "2019-07-15 00:00:00+0900",
      title: "testProgrma"
    },
        {
      yearMonthKey: "201907",
      dayKey: "15",
      startDate: "2019-07-15 00:00:00+0900",
      title: "testProgrma123132"
    }],
    16: [{
        yearMonthKey: "201907",
        dayKey: "16",
        startDate: "2019-07-15 00:00:00+0900",
        title: "testProgrma"
      }]
  },
    201908: {
      15: [{
        yearMonthKey: "201908",
        dayKey: "15",
        startDate: "2019-07-15 00:00:00+0900",
        title: "testProgrma"
      }]
    }
}

我尝试在数组方法中使用 map 来解决它。

data.map(item => {
  programs[item.yearMonthKey] : {
    programs[item.dayKey] : [{

    }]
  }
})

但是将对象排序为数组中相同 dayKey 键的值并将它们放在相同的 yearMonthKey 中有点挑战。

Answer 1

你可以 reduce阵列。将每个 yearMonthKey 添加到累加器。基于 yearMonthKey 向 acc[yearMonthKey] 对象添加一个嵌套的 dayKey 键并将其默认为数组。

const data=[{yearMonthKey:"201907",dayKey:"15",startDate:"2019-07-15 00:00:00+0900",title:"testProgrma"},{yearMonthKey:"201907",dayKey:"15",startDate:"2019-07-15 00:00:00+0900",title:"testProgrma"},{yearMonthKey:"201907",dayKey:"16",startDate:"2019-07-15 00:00:00+0900",title:"testProgrma12313"},{yearMonthKey:"201908",dayKey:"15",startDate:"2019-07-15 00:00:00+0900",title:"testProgrma"}];

const output = data.reduce((acc, o) => {
  if (!acc[o.yearMonthKey]) 
    acc[o.yearMonthKey] = {};
    
  if (!acc[o.yearMonthKey][o.dayKey]) 
    acc[o.yearMonthKey][o.dayKey] = [];
    
  acc[o.yearMonthKey][o.dayKey].push(o);
  
  return acc;
}, {})

console.log(output)