How to sort objects by date ascending order?

Question

If I have a list of object:

var objectList= LIST_OF_OBJECT;

each object in the list contains three attributes: "name", "date","gender"

How to sort the objects in the list by "date" attribute ascending order?

(the "date" attribute contain string value like "2002-08-29 21:15:31+0500")

score 29 · Answer 1 · answered Jan 20 '14 at 21:06

29

If your objects have the date information within a String field:

yourArray.sort(function(a, b) { return new Date(a.date) - new Date(b.date) })

or, if they have it within a Date field:

yourArray.sort(function(a, b) { return a.date - b.date })

answered Jan 20 '14 at 21:06

turdus-merula

8,546
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2

Congratulations for having the only sane answer here. – Tom Jul 31 '17 at 16:20
1

You don't even need `new Date` at all if they are [valid date strings](https://stackoverflow.com/questions/51715259/what-are-valid-date-time-strings-in-javascript) in the same time zone. – str Dec 10 '18 at 12:28
A small modification on this great answer for anyone using typescript: https://stackoverflow.com/a/40248661/6121634. – ericArbour Jul 04 '23 at 16:08

score 11 · Accepted Answer · answered Sep 22 '11 at 10:07

11

The Array.sort method accepts a sort function, which accepts two elements as arguments, and should return:

< 0 if the first is less than the second
0 if the first is equal to the second
> 0 if the first is greater than the second.

.

objectList.sort(function (a, b) {
    var key1 = a.date;
    var key2 = b.date;

    if (key1 < key2) {
        return -1;
    } else if (key1 == key2) {
        return 0;
    } else {
        return 1;
    }
});

You're lucky that, in the date format you've provided, a date that is before another date is also < than the date when using string comparisons. If this wasn't the case, you'd have to convert the string to a date first:

objectList.sort(function (a, b) {
    var key1 = new Date(a.date);
    var key2 = new Date(b.date);

    if (key1 < key2) {
        return -1;
    } else if (key1 == key2) {
        return 0;
    } else {
        return 1;
    }
});

answered Sep 22 '11 at 10:07

Matt

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I would start by defining a new field in each value with the date already parsed for efficiency. – Serabe Sep 22 '11 at 10:11
How about if it is not a list of objects, but a object which contain objects, and I would like to sort the objects inside a object? – Leem Sep 22 '11 at 10:13
@Leem: There is nothing in any standards which describes what order object members should be enumerated in (citation needed). You should convert the object to an array. – Matt Sep 22 '11 at 10:16
If `date` field always contains value as "2002-08-29 21:15:31+0500" and always have "+0500", then posible to compare they for sorting without parsing into `Date` object. – Andrew D. Sep 22 '11 at 10:20

score 3 · Answer 3 · edited Jun 12 '17 at 20:41

3

yourArray.sort(function(a, b) { 
 a = new Date(a.date);
 b = new Date(b.date);
 return a >b ? -1 : a < b ? 1 : 0;
})

edited Jun 12 '17 at 20:41

RredCat

5,259
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answered Jun 12 '17 at 18:39

sd.n

51
2

score -1 · Answer 4 · edited Jul 08 '23 at 11:09

-1

You can try:

var a =[-1,0,5,4,3,2,6,1,1];
var b = totzarrange(a)
console.log(b);

edited Jul 08 '23 at 11:09

kldjlkd

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answered Apr 30 '17 at 10:56

as sdfas

1
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How to sort objects by date ascending order?

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