使用该对象计数数组中的对象以及该对象的计数

Question

我有这个代码片段。并且想要计算重复的 applicationType 和 applicationType 并将两者都计算在内。

   {
    applicationType:"Supplemental Marketing Application",
    createdBy:"System"
},
{
    applicationType:"Supplemental Marketing Application",
    createdBy:"System"
},
{
    applicationType:"Orphan Application",
    createdBy:"System"
},
{
    applicationType:"Orpahn Application",
    createdBy:"System"
},
{
    applicationType:"IND/BB",
    createdBy:"System"
}

我还想计算应用程序类型以及应用程序类型名称，并希望得到这样的结果，

{
    applicationType:"Supplemental Marketing Application",
    count:"2"
},
{
    applicationType:"Orphan Application",
    count:"2"
},
{
    applicationType:"IND/BB",
    count:"1"
}

或

applicationType = [Supplemental Marketing Application,Orphan Application,IND/BB]
count = [2,2,1]

Answer 1

您可以使用 reduce 函数并检查累加器数组中是否存在其值与原始数组中 applicationType 的值匹配的键如果 findIndex ===-1 然后使用原始数组中的这些值创建一个新对象，然后推入累加器，否则如果它已经存在则更新 count

的值

let orgArray = [{
    applicationType: "Supplemental Marketing Application",
    createdBy: "System"
  },
  {
    applicationType: "Supplemental Marketing Application",
    createdBy: "System"
  },
  {
    applicationType: "Orphan Application",
    createdBy: "System"
  },
  {
    applicationType: "Orpahn Application",
    createdBy: "System"
  },
  {
    applicationType: "IND/BB",
    createdBy: "System"
  }
]
let newArray = orgArray.reduce(function(acc, curr) {
  let findIndex = acc.findIndex(function(item) {
    return item.applicationType === curr.applicationType
  });

  if (findIndex === -1) {
    let newObj = {}
    newObj.applicationType = curr.applicationType;
    newObj.count = 1
    acc.push(newObj)
  } else {
    acc[findIndex].count += 1

  }


  return acc;


}, []);

console.log(newArray)

Answer 2

您可以使用 Array.reduce() 创建地图，按应用程序类型分组。检查应用程序类型是否存在于地图中，如果它已经存在于地图中，则将计数更新为 1，否则将其映射为默认计数 1。地图上的 Object.values() 将为您提供所需的输出:

let arr = [ { applicationType:"Supplemental Marketing Application", createdBy:"System" }, { applicationType:"Supplemental Marketing Application", createdBy:"System" }, { applicationType:"Orphan Application", createdBy:"System" }, { applicationType:"Orphan Application", createdBy:"System" }, { applicationType:"IND/BB", createdBy:"System" } ];

let result = Object.values(arr.reduce((a, curr)=>{
  a[curr.applicationType] = a[curr.applicationType] || {applicationType : curr.applicationType, count : 0} ;
  a[curr.applicationType].count++;
  return a;
},{}));

console.log(result);

使用该对象计数数组中的对象以及该对象的计数

count objects from an array with that object and count of that object

javascript

reducers

reactjs