javascript - 唯一属性计数 json

Question

我有一个如下的 json 文件

 {"Teams": [
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Aug-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Aug-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
]}

提取 f3 的唯一属性值的最佳方法是什么。

在我们的示例中，我应该将唯一的 f3 属性存储在一个数组中，该数组应该具有 ["Jun-2016","May-2016","Aug-2016"]

Answer 1

使用Array#reduce 方法

var data= {"Teams": [
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Aug-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Aug-2016","color":"R"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"Jun-2016","color":"G"},
{"id":"1","f1":"Currency","f2":"All","f3":"May-2016","color":"G"},
]};

var res = data.Teams.reduce(function(arr, ele) {
  // check element already exist if not push the value to the array
  if (arr.indexOf(ele.f3) === -1) arr.push(ele.f3);
  return arr;
  // set initial value as empty array
}, []);

console.log(res);