How to combine/merge date then order by ascending in typescript

Question

How to combine or merge without duplicating or remove the same date data based on the date

[
  {date: "05/18/2021"},
  {date: "05/19/2021"},
  {date: "05/20/2021"},
  {date: "05/21/2021"},
  {date: "05/22/2021"},
  {date: "05/10/2021"},
  {date: "05/11/2021"},
  {date: "05/12/2021"},
  {date: "05/13/2021"},
  {date: "05/14/2021"},
  {date: "05/15/2021"},
  {date: "05/03/2021"},
  {date: "05/04/2021"},
  {date: "05/29/2021"},
  {date: "05/17/2021"},
  {date: "05/18/2021"},
  {date: "05/19/2021"},
  {date: "05/20/2021"},
  {date: "05/21/2021"},
  {date: "05/22/2021"},
  {date: "05/10/2021"},
  {date: "05/11/2021"},
  {date: "05/12/2021"},
  {date: "05/13/2021"},
  {date: "05/20/2021"},
  {date: "05/21/2021"},
  {date: "05/22/2021"},
  {date: "05/10/2021"},
  {date: "05/11/2021"},
  {date: "05/12/2021"},
  {date: "05/13/2021"},
  {date: "05/14/2021"},
  {date: "05/15/2021"}
]

How to merge the duplicate data and arrange the date order by ascending.

for example

[
  {date: "05/03/2021"},
  {date: "05/04/2021"},
  {date: "05/05/2021"},
  {date: "05/06/2021"},
  {date: "05/06/2021"},
  {date: "05/07/2021"},
  {date: "05/31/2021"},
  {date: "05/08/2021"},
  {date: "05/31/2021"},
  {date: "05/24/2021"},
  {date: "05/25/2021"},
  {date: "05/26/2021"}
]

to

[
  {date: "05/03/2021"},
  {date: "05/04/2021"},
  {date: "05/05/2021"},
  {date: "05/06/2021"},
  {date: "05/07/2021"},
  {date: "05/08/2021"},
  {date: "05/24/2021"},
  {date: "05/25/2021"},
  {date: "05/26/2021"},
  {date: "05/31/2021"}
]

What I'm trying to do is the merge the duplicate date and arrange it order by ascending.

Sounds like you want to do two easily searchable things... 1) [Remove duplicates from an array of objects](https://stackoverflow.com/questions/2218999/how-to-remove-all-duplicates-from-an-array-of-objects), and 2) [Sort an array of objects by date property](https://stackoverflow.com/questions/10123953/how-to-sort-an-object-array-by-date-property). Mind you, it would be a lot easier if your date strings were in ISO 8601 format — Phil, Sep 08 '21 at 04:36
Given that OP has to sort the array afterward anyway, it is safe to goes the [`Set` approach](https://stackoverflow.com/a/44601543/10317684) to remove duplicates — Ricky Mo, Sep 08 '21 at 04:50

Saeed · Answer 1 · 2021-09-08T04:59:46.880

First you have to sort your array with date.

a.sort((a, b) => {
  let tmpA = a.date.split('/');
  tmpA = `${tmpA[2]}${tmpA[0]}${tmpA[1]}` // change the format of date to YYYYMMDD

  let tmpB = b.date.split('/');
  tmpB = `${tmpB[2]}${tmpB[0]}${tmpB[1]}` // change the format of date to YYYYMMDD
  return +tmpA - +tmpB
})

Then you have to create a Set from dates. Read more about them here

let set = new Set(a.map(itm => itm.date));

Finally you have to create your array from the set

Array.from(set).map(itm => ({
  date: itm
}))

let a = [{ date: "05/18/2021" }, { date: "05/19/2021" }, { date: "05/20/2021" }, { date: "05/21/2021" }, { date: "05/22/2021" }, { date: "05/10/2021" }, { date: "05/11/2021" }, { date: "05/12/2021" }, { date: "05/13/2021" }, { date: "05/14/2021" }, { date: "05/15/2021" }, { date: "05/03/2021" }, { date: "05/04/2021" }, { date: "05/29/2021" }, { date: "05/17/2021" }, { date: "05/18/2021" }, { date: "05/19/2021" }, { date: "05/20/2021" }, { date: "05/21/2021" }, { date: "05/22/2021" }, { date: "05/10/2021" }, { date: "05/11/2021" }, { date: "05/12/2021" }, { date: "05/13/2021" }, { date: "05/20/2021" }, { date: "05/21/2021" }, { date: "05/22/2021" }, { date: "05/10/2021" }, { date: "05/11/2021" }, { date: "05/12/2021" }, { date: "05/13/2021" }, { date: "05/14/2021" }, { date: "05/15/2021" } ];

a = a.sort((a, b) => {
  let tmpA = a.date.split('/');
  tmpA = `${tmpA[2]}${tmpA[0]}${tmpA[1]}` // change the format of date to YYYYMMDD

  let tmpB = b.date.split('/');
  tmpB = `${tmpB[2]}${tmpB[0]}${tmpB[1]}` // change the format of date to YYYYMMDD
  return +tmpA - +tmpB
})

let set = new Set(a.map(itm => itm.date));

let result = Array.from(set).map(itm => ({
  date: itm
}))

console.log(
  result
)

score 0 · Answer 2 · answered Sep 08 '21 at 04:54

Given that the object structure is like what you provided:

first, remove duplicate with Set, since Set will allow you to store unique values. Remember to stringify objects before adding to Set, because { date: "05/18/2021" } and { date: "05/18/2021" } are two different object references, but the same primitive string values

The Set object lets you store unique values of any type, whether primitive values or object references.

sort by date, by converting to Date and getTime

const data = [ { date: "05/18/2021" }, { date: "05/19/2021" }, { date: "05/20/2021" }, { date: "05/21/2021" }, { date: "05/22/2021" }, { date: "05/10/2021" }, { date: "05/11/2021" }, { date: "05/12/2021" }, { date: "05/13/2021" }, { date: "05/14/2021" }, { date: "05/15/2021" }, { date: "05/03/2021" }, { date: "05/04/2021" }, { date: "05/29/2021" }, { date: "05/17/2021" }, { date: "05/18/2021" }, { date: "05/19/2021" }, { date: "05/20/2021" }, { date: "05/21/2021" }, { date: "05/22/2021" }, { date: "05/10/2021" }, { date: "05/11/2021" }, { date: "05/12/2021" }, { date: "05/13/2021" }, { date: "05/20/2021" }, { date: "05/21/2021" }, { date: "05/22/2021" }, { date: "05/10/2021" }, { date: "05/11/2021" }, { date: "05/12/2021" }, { date: "05/13/2021" }, { date: "05/14/2021" }, { date: "05/15/2021" }, ]

const rejectDuplicates = arr => {
  return Array.from(
    arr
      .map(el => JSON.stringify(el))
      .reduce((set, el) => set.add(el), new Set())
  ).map(el => JSON.parse(el))
}

const compareDateFn = ({ date: dateA }, { date: dateB }) => {
  const timeA = new Date(dateA).getTime()
  const timeB = new Date(dateB).getTime()
  return timeA - timeB
}

const res = rejectDuplicates(data).sort(compareDateFn)

console.log(res)

score 0 · Answer 3 · answered Sep 08 '21 at 04:55

You can use Set to get unique values and then use localeCompare to sort date after converting to YYYY-MM-DD format which could be lexicographically sorted.

const input = [ {date: "05/18/2021"}, {date: "05/19/2021"}, {date: "05/20/2021"}, {date: "05/21/2021"}, {date: "05/22/2021"}, {date: "05/10/2021"}, {date: "05/11/2021"}, {date: "05/12/2021"}, {date: "05/13/2021"}, {date: "05/14/2021"}, {date: "05/15/2021"}, {date: "05/03/2021"}, {date: "05/04/2021"}, {date: "05/29/2021"}, {date: "05/17/2021"}, {date: "05/18/2021"}, {date: "05/19/2021"}, {date: "05/20/2021"}, {date: "05/21/2021"}, {date: "05/22/2021"}, {date: "05/10/2021"}, {date: "05/11/2021"}, {date: "05/12/2021"}, {date: "05/13/2021"}, {date: "05/20/2021"}, {date: "05/21/2021"}, {date: "05/22/2021"}, {date: "05/10/2021"}, {date: "05/11/2021"}, {date: "05/12/2021"}, {date: "05/13/2021"}, {date: "05/14/2021"}, {date: "05/15/2021"} ],
      result = [...new Set(input.map(o => o.date))]
                .map(date => ([date, date.replace(/(..)\/(..)\/(....)/, '$3-$1-$2')]))
                .sort((a,b) => a[1].localeCompare(b[1]))
                .map(([date]) => ({date}));
console.log(result);

score 0 · Answer 4 · answered Sep 08 '21 at 05:26

Use Array.reduce() and Set to remove duplicate values and apply Array.sort() to sort the dates.

const dates = [
  { date: "05/03/2021" },
  { date: "05/04/2021" },
  { date: "05/05/2021" },
  { date: "05/06/2021" },
  { date: "05/06/2021" },
  { date: "05/07/2021" },
  { date: "05/31/2021" },
  { date: "05/08/2021" },
  { date: "05/31/2021" },
  { date: "05/24/2021" },
  { date: "05/25/2021" },
  { date: "05/26/2021" }
];

const removeDuplicateAndSort = (list) => {
  const set = new Set();
  const uniqueItems = list.reduce((finalList, dateObj) => {
    if (!set.has(dateObj.date)) {
      finalList.push(dateObj);
      set.add(dateObj.date);
    }
    return finalList
  }, []);
  return uniqueItems.sort((obj1, obj2) => new Date(obj1.date) - new Date(obj2.date));
}

console.log(removeDuplicateAndSort(dates));

How to combine/merge date then order by ascending in typescript

4 Answers4