Question

我跟随JSON，我的车主是他们的车主。在lodash中是否有更好的方法可以从预定义列表中获取汽车数量。

例如，

{
    "data": [
        {"ownerId":"00001", "make": "Honda"},
        {"ownerId":"00002", "make": "Nissan"},
        {"ownerId":"00003", "make": "Audi"},
        {"ownerId":"00004", "make": "Porsche"},
        {"ownerId":"00005", "make": "Honda"},
        {"ownerId":"00006", "make": "Honda"},
        {"ownerId":"00007", "make": "Audi"},
        {"ownerId":"00008", "make": "Volkswagen"},
        {"ownerId":"00009", "make": "Honda"},
        {"ownerId":"00010", "make": "Porsche"},
        {"ownerId":"00011", "make": "Volkswagen"}
    ]
}

计算计数的过滤器列表：

["Honda", "Audi", "Porsche"]

预期结果：

[{"Audi": 2}, {"Honda": 4}, {"Porsche": 2}]

输入JSON中还有其他汽车品牌，但由于过滤器列表没有，因此不予考虑。

Answer 1

您可以使用_.countBy()来获取和制作每个制作的计数，然后使用_.pick()您想要的项目：

＆＃13;

const cars = {"data":[{"ownerId":"00001","make":"Honda"},{"ownerId":"00002","make":"Nissan"},{"ownerId":"00003","make":"Audi"},{"ownerId":"00004","make":"Porsche"},{"ownerId":"00005","make":"Honda"},{"ownerId":"00006","make":"Honda"},{"ownerId":"00007","make":"Audi"},{"ownerId":"00008","make":"Volkswagen"},{"ownerId":"00009","make":"Honda"},{"ownerId":"00010","make":"Porsche"},{"ownerId":"00011","make":"Volkswagen"}]};

const list = ["Honda", "Audi", "Porsche"];

const result = _.pick(_.countBy(cars.data, 'make'),  ["Honda", "Audi", "Porsche"]);

console.log(result);

＆＃13;

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.5/lodash.min.js"></script>

＆＃13;

在JSON

1 个答案: