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按一个对象属性的长度对对象数组进行排序

arrays javascript

tomen · 技术社区 · 7 年前

[{
  id: 'card1',
  text: "Item1",
  votedBy: {
             userId1: true,
             userId2: true
           }
 }, 
 {
  id: 'card2',
  text: 'Item 1',
  votedBy: {
             userId3: true
           }
 }, 
 {
  id: 'card3',
  text: 'Item 3'
 }, 
{
  id: 'card4',
  text: "Item4",
  votedBy: {
             userId5: true,
             userId6: true,
             userId7: true
           }
 }]

我尝试使用Array.sort,如下所示

array.sort((a,b) => Object.keys(b.votedBy).length - Object.keys(a.votedBy).length )

而且,只有当每个对象都必须具有votedBy属性时,它才起作用。但是我的一些对象没有这个属性。

结果应该是这样的

[{
     {
      id: 'card4',
      text: "Item4",
      votedBy: {
                 userId5: true,
                 userId6: true,
                 userId7: true
               }
     },
    {
      id: 'card1',
      text: "Item1",
      votedBy: {
                 userId1: true,
                 userId2: true
               }
     }, 
     {
      id: 'card2',
      text: 'Item 1',
      votedBy: {
                 userId3: true
               }
     }, 
     {
      id: 'card3',
      text: 'Item 3'
     }, 
]

array.sort((a, b) => (
  Boolean(b.votedBy) - Boolean(a.votedBy)
  || Object.keys(b.votedBy).length - Object.keys(a.votedBy).length
));

只有当我有一个没有sortedBy的对象时,它才起作用。如果我有多个没有sortedBy的对象,则有一个错误

新的测试阵列应该是这样的

[{
  id: 'card1',
  text: "Item1",
  votedBy: {
             userId1: true,
             userId2: true
           }
 }, 
 {
  id: 'card2',
  text: 'Item 1',
  votedBy: {
             userId3: true
           }
 }, 
 {
  id: 'card3',
  text: 'Item 3'
 }, 
{
  id: 'card4',
  text: "Item4",
  votedBy: {
             userId5: true,
             userId6: true,
             userId7: true
           }
 },
 {
  id: 'card5',
  text: 'Item 5'
 } ]

更新2

我通过长而难看的代码使它工作。有没有人有更好更短的代码?

array.sort((a, b) => {
  if (a.votedBy === undefined && b.votedBy === undefined)
  return Boolean(b.votedBy) - Boolean(a.votedBy)
  else if (a.votedBy === undefined) 
  return Object.keys(b.votedBy).length - Boolean(a.votedBy)
  else if (b.votedBy === undefined) 
  return Boolean(b.votedBy) - Object.keys(a.votedBy).length
  else return Object.keys(b.votedBy).length - Object.keys(a.votedBy).length
});

1 回复 | 直到 7 年前

CertainPerformance 7 年前

第一类按是否存在差异排序 b.votedBy 和 a.votedBy :

array.sort((a, b) => (
  Boolean(b.votedBy) - Boolean(a.votedBy)
  || (
    a.votedBy &&
    Object.keys(b.votedBy).length - Object.keys(a.votedBy).length
  )
));

const array = [{
    id: 'card1',
    text: "Item1",
    votedBy: {
      userId1: true,
      userId2: true
    }
  },
  {
    id: 'card2',
    text: 'Item 1',
    votedBy: {
      userId3: true
    }
  },
  {
    id: 'card3',
    text: 'Item 3'
  },
  {
    id: 'card4',
    text: "Item4",
    votedBy: {
      userId5: true,
      userId6: true,
      userId7: true
    }
  },
  { id: 'card5', text: 'Item 5' } 
];

array.sort((a, b) => (
  Boolean(b.votedBy) - Boolean(a.votedBy)
  || (
    a.votedBy &&
    Object.keys(b.votedBy).length - Object.keys(a.votedBy).length
  )
));
console.log(array);

array.sort((a, b) => (
  Object.keys(b.votedBy || {}).length - Object.keys(a.votedBy || {}).length
));

注意,如果有可能 votedBy 要获得真实的非对象值,您必须更加详细:

(typeof b.votedBy === 'object') - (typeof a.votedBy === 'object')