I have the following array containing a JSON object defined below

[
{
    "modDate": "2017-06-20"
},
{
    "modDate": "2017-10-24"
},
{
    "modDate": "2017-08-03"
}
]

and i want the result to be grouped in first place by month and then sorted by in descending order by month.

I have tried grouping it with this

grouped_items = _.groupBy(data, (b) ->
  moment(b.modDate).startOf('month').format('YYYY/MM')

but is am not getting the correct result.

I have the following array containing a JSON object defined below

[
{
    "modDate": "2017-06-20"
},
{
    "modDate": "2017-10-24"
},
{
    "modDate": "2017-08-03"
}
]

and i want the result to be grouped in first place by month and then sorted by in descending order by month.

I have tried grouping it with this

grouped_items = _.groupBy(data, (b) ->
  moment(b.modDate).startOf('month').format('YYYY/MM')

but is am not getting the correct result.

• javascript
• momentjs
• lodash

Share Improve this question Follow edited Apr 26, 2018 at 14:05 croppio. asked Apr 26, 2018 at 13:50 croppio.croppio. 1,88355 gold badges2828 silver badges4545 bronze badges 1

• just a typo, fixed – croppio. Commented Apr 26, 2018 at 14:05

Add a ment  | 

1 Answer 1

Sorted by: Reset to default 8

If I understood you correctly, you want to create a grouped collection of the data by the month, and then sort the values descendingly by the day of month (as sorting by month in the values doesn't make sense).

If so, the following should work:

const data = [{"modDate":"2017-06-20"},{"modDate":"2017-06-25"},{"modDate":"2017-10-24"},{"modDate":"2017-10-20"},{"modDate":"2017-08-03"}];

let grouped_items = _.groupBy(data, (b) =>
  moment(b.modDate).startOf('month').format('YYYY/MM'));

_.values(grouped_items)
  .forEach(arr => arr.sort((a, b) => moment(a.modDate).day() - moment(b.modDate).day()));

console.log(grouped_items);

<script src="https://cdnjs.cloudflare./ajax/libs/lodash.js/4.17.10/lodash.js"></script>
<script src="https://cdnjs.cloudflare./ajax/libs/moment.js/2.22.1/moment.min.js"></script>