分组或汇总 Javascript 数组答案

【问题标题】：Group or summarize Javascript array分组或汇总 Javascript 数组
【发布时间】：2018-05-04 05:07:01
【问题描述】：

var json =
[
   {
      id: 11,
      name:"app1",
      family:"apps",
      caseID: 123,
      order:1
   },
   {
      id: 12,
      name:"app1",
      family:"apps",
      caseID: 123,
      order:2
   },
   {
      id: 13,
      name:"app1",
      family:"apps",
      caseID: 123,
      order:3
   },
   {
      id: 14,
      name:"app2",
      family:"tools",
      caseID: 129,
      order:1
   },
   {
      id: 15,
      name:"app2",
      family:"tools",
      caseID: 129,
      order:2
   },
   {
      id: 16,
      name:"app3",
      family:"utils",
      caseID: 120,
      order:1
   },
   {
      id: 17,
      name:"app3",
      family:"utils",
      caseID: 120,
      order:2
   },
      id: 18,
      name:"app3",
      family:"utils",
      caseID: 150,
      order:null
   }
  ]

您好，我想按最高的“order”键对上面的数组进行排序，然后返回下面的过滤数组。公共密钥是 caseID。此外，如果订单键为空，则返回它。我已经搜索并测试了一些函数和循环，但似乎无法做到。任何帮助都感激不尽。如果可能的话，我更喜欢 es2015。谢谢！

filtered = 
 [

  {
      id: 13,
      name:"app1",
      family:"apps",
      caseID: 123,
      order:3  
   },
   {
      id: 15,
      name:"app2",
      family:"tools",
      caseID: 129,
      order:2
   },
   {
      id: 17,
      name:"app3",
      family:"utils",
      caseID: 120,
      order:2
   },
   {
      id: 18,
      name:"app3",
      family:"utils",
      caseID: 150,
      order:null
   }
  ]

【问题讨论】：

我认为没有任何努力。
另外，问题没有解释从输入确定输出的逻辑。输出缺少输入中的许多元素。
你的意思是codepen.io/anon/pen/aGypVE?editors=0010 吗？
谢谢大家的回复。我将通过所有的答案来学习一两件事。

标签： javascript arrays json ecmascript-6

【解决方案1】：

我会从摆脱受骗开始。您可以使用reduce() 执行此操作，并将其分配给以caseID 为键的对象。您可以同时避免任何order 小于您已经看到的对象。然后，您可以获取该哈希的值，这将是基于 caseID 的唯一对象，并像往常一样对它们进行排序。例如：

var json = [{   "id": 11,   "name":"app1",   "family":"apps",   "caseID": 123,   "order":1},{   "id": 12,   "name":"app1",   "family":"apps",   "caseID": 123,   "order":2},{   "id": 13,   "name":"app1",   "family":"apps",   "caseID": 123,   "order":3},{   "id": 14,   "name":"app2",   "family":"tools",   "caseID": 129,   "order":1},{   "id": 15,   "name":"app2",   "family":"tools",   "caseID": 129,   "order":2},{   "id": 16,   "name":"app3",   "family":"utils",   "caseID": 120,   "order":1},{   "id": 17,   "name":"app3",   "family":"utils",   "caseID": 120,   "order":2},{   "id": 18,   "name":"app3",   "family":"utils",   "caseID": 150,   "order":null},] 

// get just the filtered items based on caseID
// picking out only the largest
let filtered = json.reduce((a,c) => {
      if (!a[c.caseID] || a[c.caseID]['order'] < c.order) a[c.caseID] = c
      return a
  }, {})

// basic sort
let result = Object.values(filtered).sort((a,b) => b.order - a.order)
console.log(result)

【讨论】：

感谢您的快速回复和解释解决方案。我从来没有想过把它分成两部分。过滤然后排序。

【解决方案2】：

如果order 更高，您可以使用caseID 哈希表并覆盖稍后找到的结果：

  const result = [], hash = {};

  for(const el in json) {
   const exists = hash[el.caseId];
   if(exists) {
     if(el.order > exists.order)
       Object.assign(exists, el);
   } else {
       result.push(hash[el.caseId] = {...el});
   }
 }

【讨论】：

【解决方案3】：

你可以试试关注

方法

创建一个对象，以唯一的案例 ID 作为键，值是最高顺序的项目
按顺序排序

// Code goes here

var json = [{"id":11,"name":"app1","family":"apps","caseID":123,"order":1},{"id":12,"name":"app1","family":"apps","caseID":123,"order":2},{"id":13,"name":"app1","family":"apps","caseID":123,"order":3},{"id":14,"name":"app2","family":"tools","caseID":129,"order":1},{"id":15,"name":"app2","family":"tools","caseID":129,"order":2},{"id":16,"name":"app3","family":"utils","caseID":120,"order":1},{"id":17,"name":"app3","family":"utils","caseID":120,"order":2},{"id":18,"name":"app3","family":"utils","caseID":150,"order":null}];
  
  
  var map = {};

  // Create a map of unique case ID's with highest order
  json.forEach((item) => {
    if(map[item.caseID]) {
        if(map[item.caseID].order < item.order) {
          map[item.caseID] = item;
        }
    } else {
      map[item.caseID] = item;
    }
  });
  
  // Sorting the array based on order
  var result = Object.values(map).sort((a,b) => b.order-a.order);
  console.log(result);

【讨论】：

【解决方案4】：

在 ES6 中：

json.sort((a, b) => a.caseID > b.caseID);
let bad_order = json.filter(v => v.order === null);
let good_order = json.filter(v => v.order !== null);

Example

在 ES5 中：

json.sort(function(a, b) { return a.caseID > b.caseID; });

var bad_order = [];
var good_order = [];

for(var i = 0; i < json.length; i++){
  if(json[i].order === null)
    bad_order.push(json[i]);
  else
    good_order.push(json[i]);
}

Example

【讨论】：

【解决方案5】：

使用reduce方法创建一个对象，其中的键将是caseID。创建对象时检查订单的值是否大于或小于当前订单值。如果当前值小于比新值，替换为新值。

然后使用Object.values(object)从对象中创建一个值数组

var json = [{
    "id": 11,
    "name": "app1",
    "family": "apps",
    "caseID": 123,
    "order": 1
  },
  {
    "id": 12,
    "name": "app1",
    "family": "apps",
    "caseID": 123,
    "order": 2
  },
  {
    "id": 13,
    "name": "app1",
    "family": "apps",
    "caseID": 123,
    "order": 3
  },
  {
    "id": 14,
    "name": "app2",
    "family": "tools",
    "caseID": 129,
    "order": 1
  },
  {
    "id": 15,
    "name": "app2",
    "family": "tools",
    "caseID": 129,
    "order": 2
  },
  {
    "id": 16,
    "name": "app3",
    "family": "utils",
    "caseID": 120,
    "order": 1
  },
  {
    "id": 17,
    "name": "app3",
    "family": "utils",
    "caseID": 120,
    "order": 2
  }, {
    "id": 18,
    "name": "app3",
    "family": "utils",
    "caseID": 150,
    "order": null
  }
]

var m = json.reduce(function(acc, curr, index) {
  if (acc[curr['caseID']] === undefined) {
    acc[curr['caseID']] = curr;

  } else {
    if (acc[curr['caseID']].order < curr.order) {
      acc[curr['caseID']] = curr;
    }
  }
  return acc;
}, {})
console.log(Object.values(m))

【讨论】：

【解决方案6】：

这应该可以帮助您过滤对象数组。

            var filteredMap = {};
            json.forEach(function (item) {
                filteredMap[item.caseID] = item;
            });
            var filteredArray = [];
            for (var key in filteredMap) {
                filteredArray.push(filteredMap[key]);
            }
            console.log(JSON.stringify(filteredArray));

【讨论】：

【解决方案7】：

按订单和caseID排序，然后按caseID过滤，代码如下：

var json =
[
   {
      id: 11,
      name:"app1",
      family:"apps",
      caseID: 123,
      order:1
   },
   {
      id: 12,
      name:"app1",
      family:"apps",
      caseID: 123,
      order:2
   },
   {
      id: 13,
      name:"app1",
      family:"apps",
      caseID: 123,
      order:3
   },
   {
      id: 14,
      name:"app2",
      family:"tools",
      caseID: 129,
      order:1
   },
   {
      id: 15,
      name:"app2",
      family:"tools",
      caseID: 129,
      order:2
   },
   {
      id: 16,
      name:"app3",
      family:"utils",
      caseID: 120,
      order:1
   },
   {
      id: 17,
      name:"app3",
      family:"utils",
      caseID: 120,
      order:2
   }, {
      id: 18,
      name:"app3",
      family:"utils",
      caseID: 150,
      order:null
   }
 ]
var obj = {}
var arr = json.sort(function(a, b) {
  return b.order - a.order
}).sort(function(a, b) {
  return a.caseId - b.caseId
}).filter(function(item, index, array){
  return obj.hasOwnProperty(item.caseID) ? false : (obj[item.caseID] = true)
})
console.log(arr)

演示：http://jsbin.com/qabehorike/edit?js,console,output

【讨论】：