计算JSON元素的出现次数\频率

Question

我有一个使用Angular开发的项目，并且我有一个JSON文件，我需要根据ngFor字段通过RaceName创建对象（分组依据）。 意思是，我需要为每个RaceName创建一个对象。

[
  {"Racename":"A1","Category":34,"Gender":"M","Work":"Amdocs","FullName":"Mark Owen"},
  {"Racename":"A1","Category":34,"Gender":"M","Work":"Amdocs","FullName":"Mark Owen"},
  {"Racename":"A2","Category":34,"Gender":"M","Work":"Amdocs","FullName":"Mark Owen"},
  {"Racename":"A3","Category":34,"Gender":"M","Work":"Amdocs","FullName":"Mark Owen"},
  {"Racename":"A4","Category":34,"Gender":"M","Work":"Amdocs","FullName":"Mark Owen"},
  {"Racename":"A5","Category":34,"Gender":"M","Work":"Amdocs","FullName":"Mark Owen"},
]

因此，根据随附的JSON，我预计只会出现5次。

HTML div标签是： <div class='table' *ngFor = 'let competition of filteredRaceName'> 但是我不确定filteredRaceName方法应该是什么样。