如何在此对象数组中查找重复值？ [关闭]

Question

    zones = [
      {zone:'A' : price:'20'},
      {zone:'B' : price:'20'},
      {zone:'C' : price:'20'},
      {zone:'A' : price:'20'},
    ];

这是我的对象数组，如果区域“A”重复两次我需要找到那个，我如何找到重复值？

Answer 1

在这里找到这个答案：post 1

 var zones = [
    {zone:'A' : price:'20'},
    {zone:'B' : price:'20'},
    {zone:'C' : price:'20'},
    {zone:'A' : price:'20'},
 ];

 unique = [...new Set(zones.map(propYoureChecking => 
    propYoureChecking.zone))];
    if (unique.length === 1) {
    console.log(unique);
 }

对于普通数组：post 2

您可以通过几种不同的方式进行操作：这是一种（来自帖子）：

 const arry = [1, 2, 1, 3, 4, 3, 5];

 const toFindDuplicates = arry => arry.filter((item, index) => arr.indexOf(item) !== index)
 const duplicateElementa = tofindDuplicates(arry);
 onsole.log(duplicateElements);

// Output: [1, 3]

Answer 2

zones = [{
    zone: 'A',
    price: '20'
  },
  {
    zone: 'B',
    price: '20'
  },
  {
    zone: 'C',
    price: '20'
  }
];

var result = []

for (let i = 0; i < zones.length; i++) {
  for (let k = 1; k < zones.length; k++) {
    if (zones[i].zone === zones[k].zone && i != k && result.indexOf(zones[i].zone) == -1) {
      result.push(zones[i].zone)
      console.log(zones[i].zone)
    }
  }
}

Answer 3

您的要求有点模糊，但假设您要查找重复对象的索引。

zones = [
{zone:'A', price:'20'},
{zone:'B', price:'20'},
{zone:'C', price:'20'},
{zone:'A', price:'20'},
];

const zoneAIndices = [];

zones.forEach((zone, index) => {
 if( zone.zone === 'A') {
   zoneAIndices.push(index);
 }
});

现在zoneAIndices[1] 具有重复项的索引。

注意：

您定义的zones 数组不正确，而不是zone 和price 之间的: 应该是,

Answer 4

您可以减少代码并简单地创建一个函数来选择键并计算出现次数，如下所示

const zones = [
{zone:'A' , price:'20'},
{zone:'B' , price:'20'},
{zone:'C' , price:'20'},
{zone:'A' , price:'20'},
];

const countRepeat = (x,field) =>  zones.filter(element => element[field]===x).length
    
    console.log(countRepeat('A','zone')) // 2
    
    console.log(countRepeat('20','price')) //4

您可以查看更多信息：https://learnjsx.com/category/2/posts/es6-filterFunction