GroupBy 数组，然后 sortBy 使用 lodash 确定该数组的日期答案

【问题标题】：GroupBy array and then sortBy date that array using lodashGroupBy 数组，然后 sortBy 使用 lodash 确定该数组的日期
【发布时间】：2021-01-25 11:08:39
【问题描述】：

我有一个这样的数组：

[
  {id: "1", description: "Insurance", date: "2020-12-22T00:00:00Z"},
  {id: "2", description: "Salary", date: "2020-12-20T00:00:00Z"},
  {id: "3", description: "Interest", date: "2020-12-20T00:00:00Z"},
  {id: "4", description: "Panera", date: "2020-12-19T00:00:00Z"},
  {id: "5", description: "Citibank", date: "2020-12-18T00:00:00Z"},
]

现在我想要 GroupBy 日期，然后是最新的 sortBy 日期，这是我的代码，我使用的是 lodash

const groups = _(list)
  .groupBy((trans) => moment(trans.date).format('MM/DD/YYYY'))
  .sortBy(group => list.indexOf(group[0]))
  .value();

上面代码的数组结果如：

[
  0: [
       {id: "1", description: "Insurance", date: "2020-12-22T00:00:00Z"}
     ],
  1: [
       {id: "2", description: "Salary", date: "2020-12-20T00:00:00Z"},
       {id: "3", description: "Interest", date: "2020-12-20T00:00:00Z"}
     ],
  2: [
       {id: "4", description: "Panera", date: "2020-12-19T00:00:00Z"}
     ]
  
  3: [
       {id: "5", description: "Citibank", date: "2020-12-18T00:00:00Z"}
     ]
]

但我希望数组返回如下：

[
  {
    date: 12/22/2020,
    items: [
       {id: "1", description: "Insurance", date: "2020-12-22T00:00:00Z"}
     ]
  },
  {
    date: 12/20/2020,
    items: [
       {id: "2", description: "Salary", date: "2020-12-20T00:00:00Z"},
       {id: "3", description: "Interest", date: "2020-12-20T00:00:00Z"}
     ],
  },
  {
    date: 12/19/2020,
    items: [
       {id: "4", description: "Panera", date: "2020-12-19T00:00:00Z"}
     ]
  },
  {
    date: 12/18/2020,
    items: [
       {id: "5", description: "Citibank", date: "2020-12-18T00:00:00Z"}
     ]
  }
]

我如何用 lodash 做到这一点。

感谢您的回答。

【问题讨论】：

您想要的输出是无效的数组/对象表示法（最外面的大括号应该是花括号而不是方括号）。
但是我有日志数组和这样的结果。无论如何，我刚刚更新了我的问题。 :))

标签： javascript arrays sorting lodash

【解决方案1】：

如果 vanilla JS 解决方案适合您，您可以使用 Array.prototype.reduce() 对您的对象进行分组，并使用 Array.prototype.sort() 对输出进行排序：

const src = [
  {id: "5", description: "Citibank", date: "2020-12-18T00:00:00Z"},
  {id: "1", description: "Insurance", date: "2020-12-22T00:00:00Z"},
  {id: "2", description: "Salary", date: "2020-12-20T00:00:00Z"},
  {id: "3", description: "Interest", date: "2020-12-20T00:00:00Z"},
  {id: "4", description: "Panera", date: "2020-12-19T00:00:00Z"},
],

      result = [...src
        .reduce((acc,o) => {
          const [yyyy, mm, dd] = o.date.split(/[\-T]/),
                key = [mm, dd, yyyy].join('/'),
                group = acc.get(key)
          group
            ? group.items.push(o)
            : acc.set(key, {date: key, items: [o]})
          return acc
        }, new Map)
        .values()]
        .sort(({date:a},{date:b}) => b.localeCompare(a))
        
console.log(result)

.as-console-wrapper{min-height:100%;}

【讨论】：