Sorting Array of Objects by date doesn't work correctly, ignores year value

Question

I have an array of objects for a project in which they work kind of like entries to a blog. I'm then attempting to sort the entries by the publication date of each entry (recents first), however, apparently the sorting function isn't considering the year value or maybe some other issue I'm missing.

Example situation

One of the entries was published the 23 of June (6) in 2019 and it is the first value of the output array because it's the entry with the most recent date. BUT if I try to change its year to something like 2005, it will stay at the top like if the function would be ignoring the year. I also tried changing it into 0 but the result remained the same.

Code I used

Example Item in the array of objects

For the date I used another array in which index 0 refers to the Day, index 1 to the Month and index 2 to the Year.

[{Id: "P3", Date: [23, 6, 2019]}, ...]

Sorting function

I use the three values of the Date arrays to calculate the total number of days since day 0 and compare them (the biggest number of days = the most recent entry)

array.sort((a, b) => ((a.Date[0] + (a.Date[1] * 30) + (a.Date[2] * 365)) < (b.Date[0] + (b.Date[1] * 30) + (b.Date[2] * 365)) ? 1 : -1)).map(item => item.Id)

The function outputs an array with the Ids of the entries they refer to, supposedly, in order.

Any help fixing my code will be helpful and appreciated :)

Some months have more than 30 days, and some years have more than 365 days. — Barmar
– Barmar, Commented Nov 7, 2019 at 2:03

codeandcloud · Accepted Answer · 2019-11-07 05:03:59Z

1

Try this.

function convertDateToNumber(date) {
  return Number(date[2] + date[1].toString().padStart(2, 0) + date[0].toString().padStart(2, 0));
}
var dates = [
  { Id: "P3", Date: [23, 6, 2019] },
  { Id: "P4", Date: [3, 6, 2019] },
  { Id: "P5", Date: [23, 12, 2019] },
  { Id: "P6", Date: [23, 7, 2019] },
  { Id: "P7", Date: [3, 12, 2019] }
];
dates.sort((a, b) => {
var aNumber = convertDateToNumber(a.Date);
var bNumber = convertDateToNumber(b.Date);
if (aNumber < bNumber) {
  return -1;
}
if (aNumber > bNumber) {
  return 1;
}
return 0;
});
console.log(dates);

edited Nov 7, 2019 at 5:03

answered Nov 7, 2019 at 4:14

codeandcloud

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Comments

rachanna · Accepted Answer · 2019-11-07 03:21:50Z

0

Use JavaScript data type 'Date' instead of array format. Then compare the dates to sort.

Change your code

[{Id: "P3", Date: [23, 6, 2019]}, ...]

to

[{Id: "P3", date: '23/6/2019'/*use proper date format*/}, ...]

With this change, you can sort the objects as below

array.sort(function(a,b){
var date1 = new Date(a.date);
var date2 = new Date(b.date);
return date1 > date2? 1:-1;
});

edited Nov 7, 2019 at 3:21

answered Nov 7, 2019 at 2:22

rachanna

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3 Comments

Bergi Over a year ago

Yes, but '23, 6, 2019' is not a proper date format!

rachanna Over a year ago

I have suggested in comment to use proper date format.

Bergi Over a year ago

But why not just use the proper date format yourself? Would make the answer so much better. You already changed the value anyway?

polunzh · Accepted Answer · 2019-11-07 03:47:23Z

0

You'd better use Date library to compare Date data, for example: moment.js.

answered Nov 7, 2019 at 3:47

polunzh

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