How to Sort an Array by Date in JavaScript
Oct 14, 2021
Sorting an array of dates is a convenient one-liner, because comparing dates in JavaScript is easy: subtracting 2 dates returns the difference between the two dates in milliseconds.
Just subtract the two dates in the sort() callback.
const dates = [
new Date('July 20, 2021 20:17:40'),
new Date('August 19, 2021 23:15:30'),
new Date('March 13, 2021 04:20'),
new Date('October 2, 2021 11:05')
];
dates.sort((date1, date2) => date1 - date2);
/*
[
2021-03-13T09:20:00.000Z,
2021-07-21T00:17:40.000Z,
2021-08-20T03:15:30.000Z,
2021-10-02T15:05:00.000Z
]
*/
dates;Sorting an Array of Objects by a Date Property
Similarly, sorting an array of objects by a date property is easy.
Just subtract the two date properties in the sort() callback.
For example, here's how you can sort an array of objects by the createdAt property.
const d1 = new Date('2019-06-01');
const d2 = new Date('2018-06-01');
const d3 = new Date('2019-06-01');
const objects = [
{ createdAt: d1, name: 'Test 1' },
{ createdAt: d2, name: 'Test 2' },
{ createdAt: d3, name: 'Test 3' }
];
objects.sort((a, b) => a.createdAt - b.createdAt);
// [ 'Test 2', 'Test 1', 'Test 3' ]
console.log(objects.map(o => o.name));Sort Without The Time
You could also sort without using the time portion of the date.
There are a couple of options, but one approach is to clone the dates and zero out the hours, minutes, seconds, and milliseconds using the setHours() function.
const dates = [
new Date('July 20, 2021 20:17:40'),
new Date('August 19, 2021 23:15:30'),
new Date('July 20, 2021 23:15:30'),
new Date('August 19, 2021 20:17:40')
];
// `setHours(0, 0, 0, 0)` zeroes out hours, minutes, seconds, and milliseconds
dates.sort((date1, date2) => new Date(date1).setHours(0, 0, 0, 0) - new Date(date2).setHours(0, 0, 0, 0));
/*
[
2021-07-21T00:17:40.000Z,
2021-07-21T03:15:30.000Z,
2021-08-20T03:15:30.000Z,
2021-08-20T00:17:40.000Z
]
*/
dates;
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