JavaScript-对数组进行分组，然后根据长度对分组结果排序

Question

这是阵列；

var dataArr = [
  {
    "permalink": /* link*/
      "subreddit": "mac"
  }, {
    "permalink": /* link*/
      "subreddit": "worldnews"
  }, {
    "permalink": /* link*/
      "subreddit": "MushroomGrowers"
  }, {
    "permalink": /* link*/
      "subreddit": "chrome"
  }, {
    "permalink": /* link*/
      "subreddit": "onions"
  }, {
    "permalink": /* link*/
      "subreddit": "onions"
  }, {
    "permalink": /* link*/
      "subreddit": "SquaredCircle"
  }.....
]

基于“ subreddit”键的分组似乎

。

简单

{
  ArtisanVideos: [
    {
      "permalink": ' link ',
      subreddit: "ArtisanVideos"
    },
    {
      "permalink": ' link ',
      subreddit: "ArtisanVideos"
    },
    {
      "permalink": ' link ',
      subreddit: "ArtisanVideos"
    }
  ],
  chrome: [
    {
      "permalink": ' link ',
      subreddit: "chrome"
    }
  ],
  laravel: [
    {
      "permalink": ' link ',
      subreddit: "laravel"
    },
    {
      "permalink": ' link ',
      subreddit: "laravel"
    },
    {
      "permalink": ' link ',
      subreddit: "laravel"
    }
  ],
  mac: [
    {
      "permalink": ' link ',
      subreddit: "mac"
    }
  ]
}

很 阵列的长度

Answer 1

从我上述评论...

“如果OP 取决于 对对象的关键插入顺序（尽管它甚至可以工作）（因为这是OP的要求），则OP的整个数据处理方法是在疑问。

问题

为了实现中间分组目标，一个人将

降低 给定的数据 - 结构为分组条目的对象（ /Developer.mozilla.org/en-us/docs/web/javascript/Reference/global_objects/objects/object/entries“ rel =“ nofollow noreferrer”> entries 现在可以是 map ped进入仍然是未排序的结果数组的对象，在最后一步中将是 sort 由每个对象的唯一数组-Value length - property或通过语言环境比较单个属性名称（键） ）。

function groupAndCollectBySameKeyValue({ key, result }, item) {
  const groupValue = item[key];
  (result[groupValue] ??= []).push(item);
  return { key, result };
}

var dataArr = [
  { permalink: 'link', subreddit: 'laravel' },
  { permalink: 'link', subreddit: 'mac' },
  { permalink: 'link', subreddit: 'ArtisanVideos' },
  { permalink: 'link', subreddit: 'laravel' },
  { permalink: 'link', subreddit: 'ArtisanVideos' },
  { permalink: 'link', subreddit: 'chrome' },
  { permalink: 'link', subreddit: 'ArtisanVideos' },
  { permalink: 'link', subreddit: 'laravel' },
];
console.log(
  dataArr
    .reduce(groupAndCollectBySameKeyValue, {
      key: 'subreddit',
      result: {},
    })
    .result
);
console.log(
  Object
    .entries(
      dataArr
        .reduce(groupAndCollectBySameKeyValue, {
          key: 'subreddit',
          result: {},
        })
        .result
    )
    // create object from grouped entry (key-value pair).
    .map(([key, value]) => ({ [key]: value }))
    .sort((a, b) =>
      // ... either by array length ...
      Object.values(b)[0].length - Object.values(a)[0].length
      // ... or by locale alphanumeric precedence.
      || Object.keys(a)[0].localeCompare(Object.keys(b)[0])
    )
);

.as-console-wrapper { min-height: 100%!important; top: 0; }

原因之一也可以实现OP的最初目标，但不建议实现。一个人不应真正取决于对象的密钥插入顺序。

function groupAndCollectBySameKeyValue({ key, result }, item) {
  const groupValue = item[key];
  (result[groupValue] ??= []).push(item);
  return { key, result };
}

var dataArr = [
  { permalink: 'link', subreddit: 'laravel' },
  { permalink: 'link', subreddit: 'mac' },
  { permalink: 'link', subreddit: 'ArtisanVideos' },
  { permalink: 'link', subreddit: 'laravel' },
  { permalink: 'link', subreddit: 'ArtisanVideos' },
  { permalink: 'link', subreddit: 'chrome' },
  { permalink: 'link', subreddit: 'ArtisanVideos' },
  { permalink: 'link', subreddit: 'laravel' },
];
console.log(
  dataArr
    .reduce(groupAndCollectBySameKeyValue, {
      key: 'subreddit',
      result: {},
    })
    .result
);
console.log(
  Object
    .entries(
      dataArr
        .reduce(groupAndCollectBySameKeyValue, {
          key: 'subreddit',
          result: {},
        })
        .result
    )
    .sort(([aKey, aValue], [bKey, bValue]) =>
      // array length first, or locale property name comparison.
      bValue.length - aValue.length || aKey.localeCompare(bKey)
    )
    .reduce((result, [key, value]) =>
      // create object by aggregating entries while following
      // the above sorted key precedence / key insertion order.
      Object.assign(result, { [key]: value }), {}
    )
);

.as-console-wrapper { min-height: 100%!important; top: 0; }