如何在具有特定不同值对的对象数组中找到值的总和？

Question

我想在具有特定用户的对象数组中查找值的总和，并为特定用户创建具有总值的不同对象数组。

这是我拥有的对象数组。

var userData = [
  {name: "user1", amount: 80},
  {name: "user1", amount: 12},
  {name: "user1", amount: 8},
  {name: "user2", amount: 60},
  {name: "user2", amount: 12},
  {name: "user3", amount: 90},
  {name: "user3", amount: 28}
]

我需要的输出。

UserGrandTotal = [
  {name: "user1", totalamount: 100},
  {name: "user2", totalamount: 72},
  {name: "user3", totalamount: 118}  
]

Answer 1

您可以通过传递一个callback提供的函数来使用reduce方法，该函数应用于数组中的每个项目。

我使用reduce创建了一个hash结构，其中我将每个唯一name存储为散列key ，作为散列值，我们有user详细信息以及该指定user总amount 。

由于算法的复杂性，我们有O(N)因为我们只迭代整个数组一次。

 var userData = [ {name: "user1", amount: 80}, {name: "user1", amount: 12}, {name: "user1", amount: 8}, {name: "user2", amount: 60}, {name: "user2", amount: 12}, {name: "user3", amount: 90}, {name: "user3", amount: 28} ]; var result = Object.values(userData.reduce((hash, item) => { if (!hash[item.name]) { hash[item.name] = { name: item.name, amount: 0 }; } hash[item.name].amount += item.amount; return hash; }, {})); console.log(result);

Answer 2

使用forEach和find给出替代答案：

 var userData = [ {name: "user1", amount: 80}, {name: "user1", amount: 12}, {name: "user1", amount: 8}, {name: "user2", amount: 60}, {name: "user2", amount: 12}, {name: "user3", amount: 90}, {name: "user3", amount: 28} ] let userGrandTotal = []; userData.forEach(user => { let grandUser = userGrandTotal.find(userGrand => userGrand.name === user.name); if(grandUser) { grandUser.amount += user.amount; } else { userGrandTotal.push(user) } }) console.log(userGrandTotal)