如何從嵌套物件重新計算物件？

我有一個物件，其中 Citems 是一個物件陣列。每個物件都具有 on 或 of 和 time 的狀態。

{
  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'
}

我想從中生成一個陣列或物件，顯示每個狀態的總時間，如下所示

{
on: 120,
off: 60
}

我嘗試使用 map 和 reduce，但感到困惑。

uj5u.com熱心網友回復：

您只需要一個嵌套的“總和”，這里使用reduce()并利用計算屬性status來使用as 鍵更新累加器。

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...of回圈

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);

要將其擴展到此類Chapter物件的陣列，您可以將其再次嵌套在reduce().

顯示代碼片段

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);

uj5u.com熱心網友回復：

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
  }
}())

標籤：javascript 数组 目的

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