减少/分组JavaScript中的数组 [英] Reducing/Grouping an array in Javascript

问题描述

基于此示例，我想以其他方式对对象进行分组.结果应该如下:

Based on this example, I want to group by object in a slightly other way. The outcome should be as follows:

[{
  key: "audi"
  items: [
    {
      "make": "audi",
      "model": "r8",
      "year": "2012"
    },
    {
      "make": "audi",
      "model": "rs5",
      "year": "2013"
    }
  ]
},
...
]

我该如何实现?我编写的以下代码无法实现我想要的功能:

How can I achieve that? The following code I wrote doesn't do what I want:

reduce(function (r, a) {
        r[a.art] = {key: r[a.art], items: []} || [];
        r[a.art].items.push(a);
        return r;
    }, Object.create(null));

推荐答案

您可以使用哈希表按make进行分组，并使用所需结果的数组.

You could use a hash table for grouping by make and an array for the wanted result.

对于hash中的每个组，都有一个新对象，例如

For every group in hash, a new object, like

{
    key: a.make,
    items: []
}

已创建并推送到结果集.

is created and pushed to the result set.

哈希表用一个真正空的对象初始化.没有原型，可以防止碰撞.

The hash table is initialized with a really empty object. There are no prototypes, to prevent collision.

var cars = [{ make: 'audi', model: 'r8', year: '2012' }, { make: 'audi', model: 'rs5', year: '2013' }, { make: 'ford', model: 'mustang', year: '2012' }, { make: 'ford', model: 'fusion', year: '2015' }, { make: 'kia', model: 'optima', year: '2012' }],
    hash = Object.create(null),
    result = [];

cars.forEach(function (a) {
    if (!hash[a.make]) {
        hash[a.make] = { key: a.make, items: [] };
        result.push(hash[a.make]);
    }
    hash[a.make].items.push(a);
});

console.log(result);

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

这篇关于减少/分组JavaScript中的数组的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！