Javascript -按每个数组中元素的升序排列数组元素

Question

我有一个数组：

arr = 
[{"nid":"MIA","keys":[{"sid":"sm1"},{"sid":"sm2"}]},

{"nid":"MID","keys":[{"sid":"sm1"}]},

{"nid":"MIT","keys":[{"sid":"sm1"},{"sid":"sm2"},{"sid":"sm3"},{"sid":"sm4"},{"sid":"sm5"},{"sid":"sm6"},{"sid":"sm7"},{"sid":"sm8"},{"sid":"sm9"},{"sid":"sm10"}]},

{"nid":"MIO","keys":[{"sid":"sm1"},{"sid":"sm2"},{"sid":"sm3"}]},

{"nid":"MIS","keys":[{"sid":"sm1"},{"sid":"sm2"}]},

{"nid":"MIH","keys":[{"sid":"sm1"}]}]

arr由6个元素组成。这六个元素中的每一个都由另一个数组keys组成。我需要按每个键数的升序重新排列这六个元素。这意味着我需要以这种方式重新排列数组：

arr = 
[

{"nid":"MID","keys":[{"sid":"sm1"}]},

{"nid":"MIH","keys":[{"sid":"sm1"}]},

{"nid":"MIA","keys":[{"sid":"sm1"},{"sid":"sm2"}]},

{"nid":"MIS","keys":[{"sid":"sm1"},{"sid":"sm2"}]},

{"nid":"MIO","keys":[{"sid":"sm1"},{"sid":"sm2"},{"sid":"sm3"}]},

{"nid":"MIT","keys":[{"sid":"sm1"},{"sid":"sm2"},{"sid":"sm3"},{"sid":"sm4"},{"sid":"sm5"},{"sid":"sm6"},{"sid":"sm7"},{"sid":"sm8"},{"sid":"sm9"},{"sid":"sm10"}]},
]

我试图获取每个数组元素的keys中的元素数，如下所示：

    var arrMap = [];
    arr.forEach(function(array_) {
        key_ = array_.keys;
        var count = 0;
        key_.forEach(function(arrKey) {
            count++;
            var keyCode = arrKey.sid;
        })
        arrMap.push({'nid':array_.nid, 'count': count});
    })
    console.log(arrMap);

这给了我以下输出：

[{"nid":"MIA","count":2},{"nid":"MID","count":1},{"nid":"MIT","count":10},{"nid":"MIO","count":3},{"nid":"MIS","count":2},{"nid":"MIH","count":1}]

现在，我对如何使用关键元素的count重新排列数组感到困惑。如有任何指导或帮助，将不胜感激！

Answer 1

你可以试试.sort

​

let arr = [ {"nid":"MIA","keys":[{"sid":"sm1"},{"sid":"sm2"}]},
{"nid":"MID","keys":[{"sid":"sm1"}]},
{"nid":"MIT","keys":[{"sid":"sm1"},{"sid":"sm2"},{"sid":"sm3"},{"sid":"sm4"},{"sid":"sm5"},{"sid":"sm6"},{"sid":"sm7"},{"sid":"sm8"},{"sid":"sm9"},{"sid":"sm10"}]},
{"nid":"MIO","keys":[{"sid":"sm1"},{"sid":"sm2"},{"sid":"sm3"}]},
{"nid":"MIS","keys":[{"sid":"sm1"},{"sid":"sm2"}]},
{"nid":"MIH","keys":[{"sid":"sm1"}]} ];

arr.sort((a, b) => a.keys.length - b.keys.length);

console.log(arr);

​

Objects/Array/sort

Answer 2

您可以通过使用数组的排序函数来实现这一点。

arr.sort(function(a,b){return a.keys.length - b.keys.length})