JavaScript sort array item after specific array id

Question

I am sorting an array of object using the date values inside each object. I now have an edge case, if thenoDate property is set to true, that object shall be sorted after the object with the id 2.

An object looks something like this:

{
    id: 1 // just simple ids 1...99
    date: ...
    noDate: true // true or false
}

Currently its sorted like this, but that does not provide the logic I need.

data.sort((a, b) => (!a.noDate - !b.noDate) || new Date(a.date) - new Date(b.date))

perhaps data.sort((a, b) => a.noDate ? -1 : new Date(a.date) - new Date(b.date) ) — mplungjan
– mplungjan, Commented Nov 2, 2021 at 19:01
@mplungjan I want to sort the object with the noDate value set to true to be sorted after the object with id 2 — juhend23d
– juhend23d, Commented Nov 2, 2021 at 19:11
@NinaScholz I created a snippet here, hope it is more understandable now :) kopy.io/N6q9Y — juhend23d
– juhend23d, Commented Nov 2, 2021 at 19:39

Nina Scholz · Accepted Answer · 2021-11-02 21:34:24Z

1

You could sort first to get all noDate: true at top of the array and then map a new array to get all top items after id: 2 object. This approach needs a finally

let
    data = [
        { id: 0, noDate: true },
        { id: 1, date: new Date('2021-10-30') },
        { id: 2, date: new Date('2020-10-30') },
        { id: 3, noDate: true },
        { id: 4, date: new Date('2021-09-30') },
        { id: 5, date: new Date('2020-09-15') },
        { id: 6, noDate: true }
    ];

data = data
    .sort((a, b) => !a.noDate - !b.noDate || a.date - b.date)
    .flatMap((a => o => {
        if (o.noDate) { a.push(o); return []; }
        if (o.id === 2) return [o, a];
        return o;
    })([]))
    .flat();

console.log(data);

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

answered Nov 2, 2021 at 21:34

Nina Scholz

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Comments

Alpfreda · Accepted Answer · 2021-11-02 19:16:29Z

1

simply

list.sort((a, b) => a.noDate ? -1 : new Date(a.date) - new Date(b.date))

Or if you want to sort by two field first sortNumber and then sorting by date

list.sort((a, b) => a.sortNumber == b.sortNumber ? new Date(a.date) - new Date(b.date): a.sortNumber - b.sortNumber)

answered Nov 2, 2021 at 19:16

Alpfreda

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1 Comment

juhend23d Over a year ago

I want to sort the object with the noDate value set to true to be sorted after the object with id 2, does this actually solve this or am I understanding something wrong?

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