javascript - 从键中提取公共(public)值并制作多维数组

Question

我有一个像这样的对象的数组:

[
{"k1":"v1","k2":27172},
{"k1":"v1","k2":15177},
{"k1":"v1","k2":19411},
{"k1":"v2","k2":30163},
{"k1":"v2","k2":23949},
{"k1":"v2","k2":23829},
{"k1":"v2","k2":27821}
]

从 k1 中提取公共(public)值并创建如下所示的多维数组的最简单方法是什么？

[
["v1", [27172, 15177, 19411]],
["v2", [30163, 23949, 23829, 27821]]
];

Answer 1

使用数组的reduce函数

var test = [
    { "k1": "v1", "k2": 27172 },
    { "k1": "v1", "k2": 15177 },
    { "k1": "v1", "k2": 19411 },
    { "k1": "v2", "k2": 30163 },
    { "k1": "v2", "k2": 23949 },
    { "k1": "v2", "k2": 23829 },
    { "k1": "v2", "k2": 27821 }
]

var out = test.reduce(function(res, obj) {
    res[obj.k1] = res[obj.k1] || [];
    res[obj.k1].push(obj.k2)
    return res;
}, {});

var result = [];
for (var key in out) {
    result.push([key, out[key]])
};

console.log(JSON.stringify(result, null, 2))

会给予

[
 ["v1", [27172, 15177, 19411]],
 ["v2", [30163, 23949, 23829, 27821]]
];