Sort array based on presence of fields in objects

Question

How can I sort array something like below if any of fields is missing?

So existing array for example is:

const users = [
    {
        id: 1, firstname: 'Jerry'
    }, {
        id: 2, firstname: 'Thomas', lastname: 'Geib'
    }, {
        id: 3
    }, {
        id: 4, lastname: 'Berg'
    }, {
        id: 5, firstname: 'Ass', lastname: 'Noob'
    }, {
        id: 6, lastname: 'Jopa'
    }
]

and the result should be sorted in this order:

Object with firstname and lastname
Object only with firstname or lastname
Object without firstname and lastname

so that it would look like:

    const users = [
        {
            id: 2, firstname: 'Thomas', lastname: 'Geib'
        }, {
            id: 5, firstname: 'Ass', lastname: 'Noob'
        }, {
            id: 1, firstname: 'Jerry'
        }, {
            id: 4, lastname: 'Berg'
        }, {
            id: 6, lastname: 'Jopa'
        }, {
            id: 3
        }
    ]

I've tried this sorting but result is not that I needed

users.sort((a,b) => {
    if (a.firstname === b.firstname) {
        return 0
    }
    if (!a.firstname) {
        return 1
    }
    return -1
});

I suppose that the least number of object fields value to be the last one in array — Ivan Burnaev
– Ivan Burnaev, Commented Jan 29, 2019 at 12:48
@hofshteyn your edit still doesn't clarify what should happen if 2 users have both firstname and lastname? — adiga
– adiga, Commented Jan 29, 2019 at 12:50

Nina Scholz · Accepted Answer · 2019-01-29 12:53:54Z

6

You could sort by the check if the property exists. At the end sort by id ascending.

const users = [{ id: 1, firstname: 'Jerry' }, { id: 2, firstname: 'Thomas', lastname: 'Geib' }, { id: 3 }, { id: 4, lastname: 'Berg' }, { id: 5, firstname: 'Ass', lastname: 'Noob' }, { id: 6, lastname: 'Jopa' }];

users.sort((a, b) => 
    ('firstname' in b && 'lastname' in b ) - ('firstname' in a && 'lastname' in a) ||
    ('firstname' in b) - ('firstname' in a) ||
    ('lastname' in b) - ('lastname' in a) ||
    a.id - b.id
);

console.log(users);

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

edited Jan 29, 2019 at 12:53

answered Jan 29, 2019 at 12:47

Nina Scholz

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Salman Arshad · Accepted Answer · 2019-01-29 13:07:19Z

2

Well, just count the number of properties each item has and sort by this number, descending:

var users = [
  {id: 1,firstname: 'Jerry'}, 
  {id: 2,firstname: 'Thomas', lastname: 'Geib'}, 
  {id: 3}, 
  {id: 4,lastname: 'Berg'}, 
  {id: 5,firstname: 'Ass',lastname: 'Noob'}, 
  {id: 6,lastname: 'Jopa'}
];
users.sort(function(a, b) {
  var aw = ('firstname' in a) + ('lastname' in a);
  var bw = ('firstname' in b) + ('lastname' in b);
  return bw - aw;
});
console.log(users);

answered Jan 29, 2019 at 13:07

Salman Arshad

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