Question

我想返回一个由小组分组的数组，其中包含gp，胜利，损失。我正在尝试通过减少来实现这一目标，但是总数并未增加。这是我的代码...

const myArr = [
  {team: 'Red', gp: 3, win:2, loss:1},
  {team: 'Black', gp: 3, win:1, loss:2},
  {team: 'Red', gp: 10, win:8, loss:2}
]

let output = myArr.reduce(
  (acc, curr) => {
    acc[curr.team] = {
      gp: acc.gp + curr.gp,
      win: acc.win + curr.win,
      loss: acc.loss + curr.loss
    };
    return acc;
  }, {
    gp: 0,
    win: 0,
    loss: 0
  }
);

console.log(output);

此代码以我需要的格式返回数组，但是gp，win，loss不会被累加，而是显示最后一个数据点。

Answer 1

您需要将一个空对象用作累加器，然后才能使用想要的键进行添加。

const
    myArr = [{ team: 'Red', gp: 3, win: 2, loss: 1 }, { team: 'Black', gp: 3, win: 1, loss: 2 }, { team: 'Red', gp: 10, win: 8, loss: 2 }],
    keys = ['gp', 'win', 'loss'],
    output = myArr.reduce((acc, curr) => {
        acc[curr.team] = acc[curr.team] || Object.assign(...keys.map(k => ({ [k]: 0})));
        keys.forEach(k => acc[curr.team][k] += curr[k]);
        return acc;
  }, Object.create(null));

console.log(output);

Answer 2

我将使用Set将项目减少到一个唯一的集合，然后将每个项目映射到一个新对象。

const teams = [{team: 'Red', gp: 3, win:2, loss:1},
{team: 'Black', gp: 3, win:1, loss:2},
{team: 'Red', gp: 10, win:8, loss:2}]

let result = [...new Set(teams.map(t => t.team))].map(team => {
  return {
    team,
    gp:   teams.reduce((sum, val) => val.team == team ? sum + val.gp   : sum, 0),
    win:  teams.reduce((sum, val) => val.team == team ? sum + val.win  : sum, 0),
    loss: teams.reduce((sum, val) => val.team == team ? sum + val.loss : sum, 0)
  }
}, [])

console.log(result)

使用归约和求和

2 个答案: