Array sorting with condition in Javascript

Question

I need to sort an array in ascending order and to put all zeros in the end.

For example [0, 0, 0, 3, 2, 1] needs to be sorted to [1, 2, 3, 0, 0, 0]. This is my code, what do I need to add to make sure all zeros are at the end?

function sort_by_field(array, field){
                return array.sort(function(a, b){
                    if( a[field] > b[field] ){
                        return 1;
                    }
                    if( a[field] < b[field] ){
                        return -1;
                    }
                    return 0;
                });
            }

Any help will be appreciated.

Amir Popovich · Accepted Answer · 2015-09-24 13:56:32Z

26

You can do something like this:

[0, 0, 0, 3, 2, 1].sort(function(a,b){ 
    if(a === 0) return 1;
    else if(b === 0) return -1;
    else return a - b;
});

answered Sep 24, 2015 at 13:56

Amir Popovich

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Comments

ryanyuyu · Accepted Answer · 2015-09-24 14:01:27Z

6

Just check the special cases for zero before your other comparisons. So the comparison function might look like this:

function(a, b) {
    if (a === b)
        return 0;
    if (a === 0)
        return 1;
    else if (b === 0)
        return -1;

    //the rest of the comparison logic
}

It's vitally important for some sorting algorithms that the comparison function is super consistent, so that's why I've gone to the extra trouble of comparing both are equal at the very beginning.

answered Sep 24, 2015 at 14:01

ryanyuyu

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Comments

Nina Scholz · Accepted Answer · 2019-02-26 08:15:47Z

4

You could take the delta of falsy values and then sort by value.

console.log([0, 0, 0, 3, 2, 1].sort((a, b) => !a - !b || a - b));

edited Feb 26, 2019 at 8:15

answered Sep 24, 2015 at 15:28

Nina Scholz

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Comments

Ben Carp · Accepted Answer · 2020-12-11 17:30:36Z

0

const sortArrByCondition = (arr, func) =>
  arr.sort((oA, oB) => func(oA, oB)? 1: func(oB, oA)? -1 : 0)

sortByCondition (arr, (a, b) => a > b);

sortByCondition works well for string, number and boolean values, as well as more complex functions that return a boolean value.

edited Dec 11, 2020 at 17:30

answered Dec 11, 2020 at 12:52

Ben Carp

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5 Comments

Bergi Over a year ago

What is (-1) ** Number(func(a, b)) supposed to achieve? This doesn't work.

Bergi Over a year ago

Still looks overcomplicated when compared to func(a, b) ? 1 : -1…

Ben Carp Over a year ago

@Bergi, Sorry about deleting my comment. I wanted to reread your reference. Do you still think it doesn't work? I agree with your latest comment and will adjust my answer accordingly.

Bergi Over a year ago

Yes, I still think that not returning 0 for equal items is not a good idea

Ben Carp Over a year ago

@Bergi I agree. Stability is important for a sorting function. Retrospectively I wouldn't add an answer. But for the sake of the discussion does my edit solve the issue?

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