I've got the array of objects:
const data = [{
"id": "1",
"effectiveDate": "2023-01-21"
}, {
"id": "2",
"effectiveDate": "2023-02-22"
}, {
"id": "3",
"effectiveDate": "2022-05-04"
}, {
"id": "4",
"effectiveDate": "2022-05-05"
}, {
"id": "5",
"effectiveDate": "2021-01-21"
}, {
"id": "6",
"effectiveDate": "2021-02-22"
}];
What I'm after is the way to sort it in the way that the object with the most current date is on index 0 and the rest of the objects are ordered ascending from the oldest to future dates, like this:
[{
"id": "4",
"effectiveDate": "2022-05-05"
}, {
"id": "5",
"effectiveDate": "2021-01-21"
}, {
"id": "6",
"effectiveDate": "2021-02-22"
}, {
"id": "3",
"effectiveDate": "2022-05-04"
}, {
"id": "1",
"effectiveDate": "2023-01-21"
}, {
"id": "2",
"effectiveDate": "2023-02-22"
}]
The way I'm sorting it is:
const orderedDates = data.sort((a, b) => {
const dateCompareResult = new Date(a.effectiveDate) - new Date(b.effectiveDate);
return dateCompareResult;
});
which obviously gives me dates sorted ascending from the past dates to the future dates with the most current date somewhere in between. How can I move the most current date object to index 0?
function getItemsInAscendingDateOrderAndClosestToNowFirst(arr) {
const time = Date.now();
const [closest, ...rest] = Array
// create a shallow copy in order to
// not mutate the original reference.
.from(arr)
// sort items by date closest to now.
.sort((a, b) => {
const aTime = new Date(a.effectiveDate).getTime();
const bTime = new Date(b.effectiveDate).getTime();
const aDelta = Math.abs(time - aTime);
const bDelta = Math.abs(time - bTime);
return (aDelta - bDelta);
});
return [
closest,
...rest
// sort all other items in ascending date order.
.sort((a, b) =>
new Date(a.effectiveDate).getTime()
- new Date(b.effectiveDate).getTime()
),
];
}
const data = [{
"id": "1",
"effectiveDate": "2023-01-21"
}, {
"id": "2",
"effectiveDate": "2023-02-22"
}, {
"id": "3",
"effectiveDate": "2022-05-04"
}, {
"id": "4",
"effectiveDate": "2022-05-05"
}, {
"id": "5",
"effectiveDate": "2021-01-21"
}, {
"id": "6",
"effectiveDate": "2021-02-22"
}];
const sortedData =
getItemsInAscendingDateOrderAndClosestToNowFirst(data);
console.log({ sortedData });.as-console-wrapper { min-height: 100%!important; top: 0; }I think the simplest way is to sort from oldest to newest, then move the element that's closest to today to the start, e.g.
let data = [{"id": "1","effectiveDate": "2023-01-21"},
{"id": "2","effectiveDate": "2023-02-22"},
{"id": "3","effectiveDate": "2022-05-04"},
{"id": "4","effectiveDate": "2022-05-05"},
{"id": "5","effectiveDate": "2021-01-21"},
{"id": "6","effectiveDate": "2021-02-22"}];
// Sort from oldest to youngest
data.sort((a, b) => b.effectiveDate.localeCompare(a.effectiveDate));
// Get today as milliseconds
let today = new Date().toLocaleDateString('en-CA');
let todayMS = Date.parse(today);
// Get index of closest element to today
let closestIndex = data.reduce((acc, obj, index) => {
let diff = Math.abs(Date.parse(obj.effectiveDate) - todayMS);
return acc.diff > diff? {diff, index} : acc;
}, {diff: Infinity, index:null}).index;
// Move closest element to start of array
data.unshift(data.splice(closestIndex, 1));
console.log(data);One of the benefits of ISO 8601 formatted timestamps is that lexical comparisons give correct results. If you don't want to use string comparison then the comparison function can be:
data.sort((a, b) => Date.parse(b) - Date.parse(a))
but only if the timestamps are in one of the 3 formats supported by ECMA-262 (and fortunately, YYYY-MM-DD is one such format). :-)