Sort array of objects by booleans, then by numbers (javascript)

Question

I have an array of objects, and I would like to sort them following these two rules (in order of priority):

The objets whose "departeYet" property is true must be at the beginning The objects must then be sorted in numerical order (the "number" property)

This would be ok:

true : 005
true : 007
true : 027
false: 009
false: 020

This is the structure of the part of the objects that interests us:

var notSortedData = {
                        number: number, // it's a string
                        departedYet: scheduled_date, // true or false
                    }

                    sortedTrains.push(notSortedData);

So, notSortedData is pushed in sortedTrains via a for loop.

Then, I need to sort it:

sortedTrains.sort(function(a, b) {
        // sorting algorithm here
    });

What should I do? Thanks.

I do not believe you understand how sort function works and what it's parameter function should return. See the docs. Short answer: you do not need to implement a sorting algorithm, all you need is a compare function. — PM 77-1
– PM 77-1, Commented Oct 26, 2014 at 2:16

Jonathan Gray · Accepted Answer · 2018-08-06 04:46:59Z

13

You can use this original answer (which I purposely made more verbose):

sortedTrains.sort(function(a, b) {
    if(a.departedYet === b.departedYet)
        return a.number-b.number;
    else if(a.departedYet)
        return -1;
    else return 1;
});

... or this even shorter equivalent:

sortedTrains.sort(function(a, b) {
    if(a.departedYet === b.departedYet)
        return a.number-b.number;
    return a.departedYet ? -1 : 1;
});

edited Aug 6, 2018 at 4:46

answered Oct 26, 2014 at 2:37

Jonathan Gray

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2 Comments

Damir Beylkhanov Over a year ago

this version of sort is more general sortedTrains.sort(function(a, b) { if(a.departedYet === b.departedYet) return 0; else if(a.departedYet) return -1; else return 1; });

Jonathan Gray Over a year ago

@DamirBeylkhanov Your method will only sort by the departedYet value, it ignores the number value entirely.

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