如何从嵌套对象重新计算对象？

Question

我有一个对象，citem是一个对象。每个对象都具有或时间和时间。

{
  Chapter: [
    {
      Cname: 'chapter 1',
      Citems: [{status: 'on', time: 30},{status: 'on', time: 60}],
      
    },
    {
      Cname: 'chapter 2',
      Citems: [{status: 'on', time: 30},{status: 'off', time: 60}]
    }
  ],
  name: 'Something',
  description: 'jfdgljfgdfjgldfkjglfd'
}

我想从中生成一个数组或对象，以显示每个状态的总时间，例如

{
on: 120,
off: 60
}

我在地图上尝试的，并减少但感到困惑。

Answer 1

您只需要一个嵌套的“总和”，此处使用 redair（） 并利用计算属性使用status status作为键更新累加器。

const data = { Chapter: [{ Cname: 'chapter 1', Citems: [{ status: 'on', time: 30 }, { status: 'on', time: 60 }], }, { Cname: 'chapter 2', Citems: [{ status: 'on', time: 30 }, { status: 'off', time: 60 }] }], name: 'Something', description: 'jfdgljfgdfjgldfkjglfd' };

const result = data.Chapter.reduce((a, { Citems }) => {
  for (const { status, time } of Citems) {
    a[status] += time;
  }
  return a;
}, { on: 0, off: 0 });

console.log(result);

或使用 for。 .. 循环

const data = { Chapter: [{ Cname: 'chapter 1', Citems: [{ status: 'on', time: 30 }, { status: 'on', time: 60 }], }, { Cname: 'chapter 2', Citems: [{ status: 'on', time: 30 }, { status: 'off', time: 60 }] }], name: 'Something', description: 'jfdgljfgdfjgldfkjglfd' }

const result = { on: 0, off: 0 };

for (const { Citems } of data.Chapter) {
  for (const { status, time } of Citems) {
    result[status] += time;
  }
}

console.log(result);

要将其扩展到此类章对象的数组，您可以将其再次嵌套在redaim（）中。

const data = [
  {
    Chapter: [{ Cname: 'chapter 1', Citems: [{ status: 'on', time: 30 }, { status: 'on', time: 60 }], }, { Cname: 'chapter 2', Citems: [{ status: 'on', time: 30 }, { status: 'off', time: 60 }] }],
    name: 'Something',
    description: 'jfdgljfgdfjgldfkjglfd'
  },
  {
    Chapter: [{ Cname: 'chapter 1', Citems: [{ status: 'on', time: 30 }, { status: 'off', time: 30 }], }, { Cname: 'chapter 2', Citems: [{ status: 'on', time: 30 }, { status: 'off', time: 60 }] }],
    name: 'Something2',
    description: 'asdfasdfasdfasdfasdfa'
  }
]

const result = data.reduce((a, { name, Chapter }) => {
  a[name] = Chapter.reduce((a, { Citems }) => {
    for (const { status, time } of Citems) {
      a[status] += time;
    }
    return a;
  }, { on: 0, off: 0 });

  return a;
}, {});

console.log(result);

Answer 2

let obj = {Chapter: [{_id: '624568b157da1d351910c576',Cname:'chapter 1',Citems: [{status: 'on',time: 30},{status: 'on',time: 60}],},{_id:'456a5857da1d351910c577',Cname: 'chapter 2',Citems: [{status:'on',time: 30},{status: 'off',time: 60}]}],_id: '6245f975d17514e0eb9092f7',name:'Something',description:'fdgljfgdfjgldfkjglfd'}
console.log(function() {
  let on=0, off=0; //define return variables (if there is not 'on' or 'off' element at the object, the amount is 0)
  obj['Chapter'].forEach(function(elem) {
    if (elem['Citems']) { //if the list item of 'Chapter' does not have a 'Citems' attribute, we will not deal with it
      elem['Citems'].forEach(function(e) {
        if (e['status'] == 'on') {on += e['time']} else if (e['status'] == 'off') {off += e['time']}
      })
    }
  });
  return {
    on: on,
    off: off
  }
}())