Question

如果缺少任何字段，如何对数组进行如下排序？

例如，现有数组为：

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'
    }
]

，结果应按以下顺序排序：

具有firstname和lastname的对象
仅具有firstname或lastname的对象
没有firstname和lastname的对象

看起来像这样：

    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
        }
    ]

我已经尝试过这种排序，但结果不是我需要的

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

Answer 1

您可以通过检查属性是否存在来进行排序。最后按id升序排序。

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);

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Answer 2

好吧，只需计算每一项所具有的属性数量并按该数字排序，降序为：

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);

根据对象中字段的存在对数组进行排序

2 个答案: