对数组进行分组，然后对值求和答案

【问题标题】：Grouping an Array and then summing values对数组进行分组，然后对值求和
【发布时间】：2021-07-12 04:20:52
【问题描述】：

我有这个结构中的数据从我的节点进入我的 React。

[
{Field: Data, WinningPlayer: "Name1", Points: 3}
{Field: Data, WinningPlayer: "Name2", Points: 8}
{Field: Data, WinningPlayer: "Name1", Points: 4}
{Field: Data, WinningPlayer: "Name2", Points: 2}
]

我如何在 WinningPlayer 上进行分组，然后对该玩家的值求和。我浏览了一些帖子，但我无法理解如何使用 reduce 或任何其他数组函数。有人可以帮忙吗？

【问题讨论】：

stackoverflow.com/questions/19233283/… 这没有帮助？
这能回答你的问题吗？ group by, and sum, and generate a object for each array javascript，或How to group by and sum an array of objects?，或Sum javascript object propertyA values with same object propertyB in array of objects

标签： javascript arrays

【解决方案1】：

如果我正确理解了您的问题，这应该可以解决问题：

playerPoints = [
{Field:'', WinningPlayer: "Name1", Points: 3},
{Field: '', WinningPlayer: "Name2", Points: 8},
{Field: '', WinningPlayer: "Name1", Points: 4},
{Field: '', WinningPlayer: "Name2", Points: 2},
];

summedUpPoints = {}

playerPoints.forEach(data => {
    if( typeof summedUpPoints[data.WinningPlayer] === 'undefined'){
    summedUpPoints[data.WinningPlayer] = data.Points;
  }else{
    summedUpPoints[data.WinningPlayer] += data.Points;
  }
});

console.log(summedUpPoints);

【讨论】：

【解决方案2】：

我个人会为此使用Array.prototype.reduce 函数：

const data = [{WinningPlayer: "Name1", Points: 3},{WinningPlayer: "Name2", Points: 8},{WinningPlayer: "Name1", Points: 4},{WinningPlayer: "Name2", Points: 2}];

const out = data.reduce((acc, entry) => {
  if (acc[entry.WinningPlayer]) acc[entry.WinningPlayer] += entry.Points;
  else acc[entry.WinningPlayer] = entry.Points;
  return acc;
}, {} /* <-- starting object */ );

console.log(out);

【讨论】：

【解决方案3】：

你可以像这样使用Array.prototype.reduce()：

const input = [
  { Field: "Data", WinningPlayer: "Name1", Points: 3 },
  { Field: "Data", WinningPlayer: "Name2", Points: 8 },
  { Field: "Data", WinningPlayer: "Name1", Points: 4 },
  { Field: "Data", WinningPlayer: "Name2", Points: 2 },
];

const result = input.reduce((acc, cur) => {
  const found = acc.find((x) => x.WinningPlayer === cur.WinningPlayer);
  found ? (found.Points += cur.Points) : acc.push(cur);
  return acc;
}, []);

console.log(result);

【讨论】：