如何获取id与parentId匹配的元素的totalCount

Question

我有以下结构：

const arr = [
  { id: 1, count: 0, parentId: null },
  { id: 2, count: 30, parentId: 1 },
  { id: 3, count: 1, parentId: 2 }
];

我想得到这个结果

const res = [
  { id: 1, totalCount: 30 },
  { id: 2, totalCount: 31 },
  { id: 3, totalCount: 1 },
]

Answer 1

您需要遍历数组，过滤出与父 ID 匹配的项目，并使用 reduce() 对计数求和，并将其添加到每个项目的现有计数中。

const arr = [
  { id: 1, count: 0, parentId: null },
  { id: 2, count: 30, parentId: 1 },
  { id: 3, count: 1, parentId: 2 }
];

const result= [];
arr.forEach((item)=> {
  const  id = item.id;
  const items = arr.filter(x => x.parentId === item.id);
  const totalCount = item.count +  items.reduce((partialSum, a) => partialSum + a.count, 0);
  result.push({id,totalCount})
})

 console.log(result); // gives the following
 /*[
  {id: 1, totalCount:30}, 
  {id: 2, totalCount:31},
  {id: 3, totalCount: 1} 
]*/

Answer 2

此代码将为您提供所需的结果：

const arr = [
    { id: 1, count: 0, parentId: null },
    { id: 2, count: 30, parentId: 1 },
    { id: 3, count: 1, parentId: 2 }
];
const newArr = arr.map((element) => {
    const parent = arr.find((item) => {
        return item.parentId === element.id
    });
    const totalCount = parent ? element.count + parent.count : element.count;
    return {id: element.id, totalCount};
});
console.log(newArr);

如何获取id与parentId匹配的元素的totalCount

How to get totalCount of elements where id matches parentId

javascript

arrays