GroupBy array and then sortBy date that array using lodash

Question

I have an array like so:

[
  {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"},
]

Now I want GroupBy date, then sortBy date newest, here is my code, I'm using lodash

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

The array result of code above like:

[
  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"}
     ]
]

But I would like the array to return like below:

[
  {
    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"}
     ]
  }
]

How I can do this with lodash.

Thank for your answer.

Answer 1

If vanilla JS solution works for you, you can make use of Array.prototype.reduce() to group your objects and Array.prototype.sort() to sort the output:

 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)

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