查找相同键值的JSON对象的长度

Question

我有一个JSON文件。我想找到一个键值对相似的JSON对象的长度。喜欢，

https://api.myjson.com/bins/h5mgv

[
  {
    "receive_date": "2013-11-04",
    "responses": "2",
    "name": "west"
  },
  {
    "receive_date": "2013-11-04",
    "responses": "8668",
    "name": "west"
  },
  {
    "receive_date": "2013-11-13",
    "responses": "121",
    "name": "east"
  }
]

在上面的示例中，长度为2，"name": "west"，长度为1 "name": "east"。我想迭代JSON并使用Javascript为键name找到相同的值。输出应该看起来像，

east : 1
west : 2

通过使用length()，我可以找到整个JSON的长度，但建议的方法是查找相同键值的长度。

Answer 1

您可以使用reduce来获取列出每个名称计数的新对象：

const myArray = [
  {
    "receive_date": "2013-11-04",
    "responses": "2",
    "name": "west"
  },
  {
    "receive_date": "2013-11-04",
    "responses": "8668",
    "name": "west"
  },
  {
    "receive_date": "2013-11-13",
    "responses": "121",
    "name": "east"
  }
]

const myCounts = myArray.reduce((counts, item) => {
  if (counts[item.name] === undefined) counts[item.name] = 0;
  counts[item.name]++;
  return counts;
}, {});

console.log(myCounts);

这会产生结果：

{
  "west": 2,
  "east": 1
}