如何从JavaScript中的数组对象中计数唯一值 [英] How to count unique value from object of array in javascript

问题描述

我想计算唯一值的数量并将其放入新数组中. 我有下面的数组:

I want to calculate number of unique value and put that in new array. I have below array:

[
  { CategoryId: "b5c3f43f941c", CategoryName: "Category 1", CategoryColor: "cgreen" }
  { CategoryId: "9872cce5af92", CategoryName: "Category 2", CategoryColor: "purple" }
  { CategoryId: "b5c3f43f941c", CategoryName: "Category 1", CategoryColor: "cgreen" }
]

我想要具有以下结果的新数组:

I want new array with below result:

[
    { CategoryId: "b5c3f43f941c", count: 2, CategoryColor: "cgreen" }
    { CategoryId: "9872cce5af92", count: 1, CategoryColor: "purple" }
]

在此ID中检查ID是否为相同的显示计数并在新数组中是新的.

In this check by id, if id is same show count and new in new array.

希望你能理解我想要的东西.

Hope you understand what I want.

谢谢

推荐答案

您可以使用"for..of"遍历数组，并创建一个临时对象以在每次循环中保存数据.如果tempObject中存在相同的ID，则将计数加1

You can loop through array using "for..of" and create a temporary object to save data in every loop. If same id exists in tempObject then increment count by 1

var arr = [
  { CategoryId: "b5c3f43f941c", CategoryName: "Category 1", CategoryColor: "cgreen" }
  , { CategoryId: "9872cce5af92", CategoryName: "Category 2", CategoryColor: "purple" }
  , { CategoryId: "b5c3f43f941c", CategoryName: "Category 1", CategoryColor: "cgreen" }
]

var tempResult = {}

for(let { CategoryColor, CategoryId } of arr)
  tempResult[CategoryId] = { 
      CategoryId, 
      CategoryColor, 
      count: tempResult[CategoryId] ? tempResult[CategoryId].count + 1 : 1
  }      

let result = Object.values(tempResult)

console.log(result)

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