javascript - 分组或汇总Javascript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
   }
  ]

您好，我想按最高的“ order”键对上方的数组进行排序，然后返回下方的过滤后的数组。公用密钥是caseID。另外，如果订单密钥为null，则将其返回。
我已经搜索并测试了一些函数和循环，但似乎无法使其实用。任何帮助都感激不尽。如果可能，我希望使用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
   }
  ]

最佳答案

我将从摆脱骗局开始。您可以使用reduce()并将其分配给键为caseID的对象。您可以同时避免任何order小于已见对象的对象。然后，您可以获取该哈希值（将是基于caseID的唯一对象）的值，然后像通常那样对它们进行排序。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)