查找相同键值的 JSON 对象的长度 [重复]

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"。我想遍历 JSON 并使用 Javascript 找到键 name 的相同值。输出应该是这样的，

east : 1
west : 2

通过使用length()，我可以找到整个 JSON 的长度，但推荐的方法是找到相同键值的长度。

Answer 1

您可以使用 reduce 来获取一个列出每个名称的计数的新对象：

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
}