查找具有重复项的索引

Question

我会发现从 array1 到 array2 的 Indeces 有重复项。

var array1 =
[ 
 {homeTeam: 'Yokohama FC'},
 {homeTeam: 'Shonan Bellmare'},
 {homeTeam: 'K. Frontale'},
 {homeTeam: 'Cerezo Osaka'},
 {homeTeam: 'Nagoya G.'},
 {homeTeam: 'Gamba Osaka'}
]

var array2 =
[ 
 {homeTeam: 'Yokohama FC'},
 {homeTeam: 'Shonan Bellmare'},
 {homeTeam: 'K. Frontale'},
 {homeTeam: 'Cerezo Osaka'},
 {homeTeam: 'Nagoya G.'},
 {homeTeam: 'K. Frontale'},
 {homeTeam: 'Cerezo Osaka'},
 {homeTeam: 'Nagoya G.'},
 {homeTeam: 'Gamba Osaka'}
]

我的输出应该是：

[ 
 {homeTeam: 'Yokohama FC', IndexInArr2: [0] },
 {homeTeam: 'Shonan Bellmare', IndexInArr2: [1] },
 {homeTeam: 'K. Frontale', IndexInArr2: [2 , 5] },
 {homeTeam: 'Cerezo Osaka', IndexInArr2: [3 , 6] },
 {homeTeam: 'Nagoya G.', IndexInArr2: [4 , 7] },
 {homeTeam: 'Gamba Osaka', IndexInArr2: [0]}
]

我试图创建一个结果不佳的函数

function findIndex(array, attr, value){
    for(var i = 0; i < array.length; i+=1){
      if(array[i][attr] == value){
      return i
      }
    }
    return -1
}

感谢您的最终回答

Answer 1

你很接近！不要在找到第一次出现时返回，而是将它们保存在数组中并仅在最后返回。我已经做到了，所以它在找不到时返回一个空数组而不是-1，但是如果需要，您可以测试数组的长度以仍然返回-1，但我认为总是返回一个数组更好一个通用函数。

function findIndex(array, attr, value){
    const indices = [];
    for(var i = 0; i < array.length; i+=1){
      if(array[i][attr] == value){
         indices.push(i);
      }
    }
    return indices;
}

Answer 2

您也可以使用这种方法。在array1 上运行map，然后将每个项目homeTeam 的值与array2 进行比较，然后使用reduce 对索引进行分组

const array1 = [
  { homeTeam: "Yokohama FC" },
  { homeTeam: "Shonan Bellmare" },
  { homeTeam: "K. Frontale" },
  { homeTeam: "Cerezo Osaka" },
  { homeTeam: "Nagoya G." },
  { homeTeam: "Gamba Osaka" }
];
const array2 = [
  { homeTeam: "Yokohama FC" },
  { homeTeam: "Shonan Bellmare" },
  { homeTeam: "K. Frontale" },
  { homeTeam: "Cerezo Osaka" },
  { homeTeam: "Nagoya G." },
  { homeTeam: "K. Frontale" },
  { homeTeam: "Cerezo Osaka" },
  { homeTeam: "Nagoya G." },
  { homeTeam: "Gamba Osaka" }
];

const result = array1.map((item) => {
  const { homeTeam } = item;
  const result = array2.reduce(
      (accumulator, current, index) =>
      current.homeTeam === homeTeam ? [...accumulator, index] : accumulator,[]);
  return { homeTeam, IndexInArr2: result };
});

console.log(result);