How to count unique value from object of array in javascript

Question

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

[
  { CategoryId: \"b5c3f43f941c\", CategoryName: \"Category 1\", Categ         


        

Answer 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)