Sort array by current date

Question

I am looking to sort the values in an array based on the current date.

My values :

[{
  date: "12-28",
  id: 1
}, {
  date: "11-30",
  id: 2
}, {
  date: "09-30",
  id: 3
}, {
  date: "05-30",
  id: 4
}]

I tried to do something like this, but it doesn't really work :

var array = [{id: 1, date:'12-28'}, 
{id: 2, date:'11-30'}, 
{id: 3, date:'09-30'}, 
{id: 4, date:'05-30'}];

const now = Date.now();

array.sort(function(a, b) {     
    var c = new Date(a.date);
    var d = new Date(b.date);
    return (now-c)-(now-d);
});

console.log(array);

If it's November 29th :

[{
  date: "11-30",
  id: 2
}, {
  date: "12-28",
  id: 1
}, {
  date: "05-30",
  id: 4
}, {
  date: "09-30",
  id: 3
}]

Can you add an example of the output you are wanting the data in? — Drew
– Drew, Commented Nov 29, 2021 at 19:13
You want to sort them by how close they are to the current date? If so then 2000-12-28 will be the closest to 2021-11-29. — skara9
– skara9, Commented Nov 29, 2021 at 19:17
Hello, I mainly want to sort by month and day, the year doesn't really matter to me — Creatz
– Creatz, Commented Nov 29, 2021 at 20:53
I dont understand your ordering based on your output if sorting by Nov 29th. Are you trying to put any dates after Nov 29th first and then any dates before last? — Drew
– Drew, Commented Nov 29, 2021 at 21:17
Let me try to put it another way. Let's say that each date is a birthday. I want to be able to display the next birthdays based on the current date. If it's November 29th, the next birthdays are : 11-30 , 12-28, 05-30, 09-30 — Creatz
– Creatz, Commented Nov 29, 2021 at 21:55

PeterKA · Accepted Answer · 2021-12-06 13:40:11Z

1

How about turning mm-dd to mmdd and then converting to number and then using Math.abs() as follows?

const arr = [
    {date: "12-28",id: 1}, 
    {date: "11-30",id: 2}, 
    {date: "09-30",id: 3}, 
    {date: "05-30",id: 4}
];

const dt = new Date();
const now = +[dt.getMonth()+1, dt.getDate()].map(v => `0${v}`.slice(-2)).join('');

const ordered = arr.sort((a,b) => Math.abs(+a.date.replace(/[^\d]+/,'') - now) - Math.abs(+b.date.replace(/[^\d]+/,'') - now));

console.log( ordered );

All Dates Future

If all dates are to be considered to be present or future, here is a concept we can employ:

const arr = [
    {date: "12-28",id: 1}, 
    {date: "11-30",id: 2}, 
    {date: "09-30",id: 3}, 
    {date: "05-30",id: 4}
];

//converts m-d to mm-dd
const fmt = md => md.split('-').map(p => `0${p}`.slice(-2)).join('-');
const now = new Date();
const year = new Date().getFullYear();
const nww = fmt(`${now.getMonth()+1}-${now.getDate()}`);
const nw = new Date(`${year}-${nww}`).getTime();

const ordered = arr.map(({
    date: d,
    id
}) => ({
    date: d,
    id,
    d: `${d < nww ? (year + 1) : year}-${d}`
})).map(({
    d,
    ...rest
}) => ({
    ...rest,
    d,
    ...{
        t: new Date(d).getTime()
    }
})).sort((a, b) => (a.t - nw) - (b.t - nw)).map(({
    date,
    id
}) => ({
    date,
    id
}));

console.log( ordered );

edited Dec 6, 2021 at 13:40

answered Nov 30, 2021 at 0:27

PeterKA

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7 Comments

Creatz Over a year ago

Hello, Thank you very much for your help. However, this is not quite the result I want. The result should be in this order: 11-30 , 12-28, 05-30, 09-30

PeterKA Over a year ago

...next birthdays based on the current date... So you want to take all the dates as being in the future? That changes everything; will take a look shortly.

Creatz Over a year ago

That's exactly it, and I know it's not a simple thing to do ;)

PeterKA Over a year ago

Check out the second option that takes much of the processing away from the sort function.

Creatz Over a year ago

That's exactly it! It's really perfect! A huge thank you!

|

Terry Lennox · Accepted Answer · 2021-11-29 19:29:42Z

0

You can use Array.sort() to give you the desired result, I've moved the dates in the input array to this year:

let input = [{ date: "2021-12-28", id: 1 }, { date: "2021-11-30", id: 2 }, { date: "2021-09-30", id: 3 }, { date: "2021-05-30", id: 4 }];

function sortByNearest({ date: a}, {date: b}) {
    const now = Date.now();
    return (Math.abs(Date.parse(a) - now)) - (Math.abs(Date.parse(b) - now));
}

console.log(input.sort(sortByNearest))

.as-console-wrapper { max-height: 100% !important; top: 0; }

answered Nov 29, 2021 at 19:29

Terry Lennox

30.9k5 gold badges37 silver badges45 bronze badges

3 Comments

Creatz Over a year ago

Thank you very much for your answer. Nevertheless, the result is not exactly correct. Indeed, the ids should be in this order: 2, 1, 4, 3 (2021-11-30, 2021-12-28, 2021-05-30, 2021-09-30)

Terry Lennox Over a year ago

Oh cool, I'm just not sure why 2021-05-30 has a higher sort order than 2021-09-30. Could you explain this? Thanks!

Creatz Over a year ago

Indeed, I understand that my request is not very logical. In fact, the year is not really necessary, I mainly want to sort by months and days. I've modified my question, hoping that it will be a bit clearer.

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