Javascript-仅返回对象数组中的唯一值 [英] Javascript - Return only unique values in an array of objects

问题描述

我有一个对象数组，我只想根据它们的对象ID返回唯一对象。

I have an array of objects where I want to return only the unique objects based on their object Id.

我试图在现有数组中循环 data ，然后查找元素是否已添加到新创建的数组 arr 中，该数组应仅包含唯一值，但是没和我一起工作，我相信我在这里或那里缺少什么。

I've tried to loop in the existing array data then find if the element was already add to a newly created array arr which should contain only the unique values, but it didn't work with me and I believe that I am missing something here or there.

这是当前数组：

          [
        {
          "objectId": "WMtwbyhFI6",
          "cuisineNameEn": "Cafe",
          "ordersNo": 20,
          "hidden": false
        },
        {
          "objectId": "QJSNTMpq5F",
          "ordersNo": 24,
          "cuisineNameEn": "Italian",
          "hidden": false
        },
        {
          "objectId": "iLXKswFRGa",
          "ordersNo": 5,
          "cuisineNameEn": "Japanese",
          "hidden": true
        },
        {
          "objectId": "Db0MeihpJE",
          "ordersNo": 6,
          "cuisineNameEn": "Fast Food",
          "hidden": false
        },
        {
          "objectId": "QJSNTMpq5F",
          "ordersNo": 24,
          "cuisineNameEn": "Italian",
          "hidden": false
        },
        {
          "objectId": "Db0MeihpJE",
          "ordersNo": 6,
          "cuisineNameEn": "Fast Food",
          "hidden": false
        },
        {
          "objectId": "Db0MeihpJE",
          "ordersNo": 6,
          "cuisineNameEn": "Fast Food",
          "hidden": false,
        },
        {
          "objectId": "Db0MeihpJE",
          "ordersNo": 6,
          "cuisineNameEn": "Fast Food",
          "hidden": false
        },
         {
          "objectId": "Db0MeihpJE",
          "ordersNo": 6,
          "cuisineNameEn": "Fast Food",
          "hidden": false
        },
         {
          "objectId": "Db0MeihpJE",
          "ordersNo": 6,
          "cuisineNameEn": "Fast Food",
          "hidden": false
        },
        {
          "objectId": "Db0MeihpJE",
          "ordersNo": 6,
          "cuisineNameEn": "Fast Food",
          "hidden": false
        }
      ]

但是，这就是我要返回的内容：

 [
        {
          "objectId": "WMtwbyhFI6",
          "cuisineNameEn": "Cafe",
          "ordersNo": 20,
          "hidden": false
        },
        {
          "objectId": "iLXKswFRGa",
          "ordersNo": 5,
          "cuisineNameEn": "Japanese",
          "hidden": true
        },
        {
          "objectId": "Db0MeihpJE",
          "ordersNo": 6,
          "cuisineNameEn": "Fast Food",
          "hidden": false
        },
        {
          "objectId": "QJSNTMpq5F",
          "ordersNo": 24,
          "cuisineNameEn": "Italian",
          "hidden": false
        }
      ]

我尝试了以下操作：

 var arr = [];
  data.forEach((el)=>{
  if (arr.indexOf(el.objectId) === -1) {
    arr.push(el)
  }
 })

但是，它没有用。

推荐答案

使用 reduce（）方法：

data.reduce((acc, x) =>
   acc.concat(acc.find(y => y.ordersNo === x.ordersNo) ? [] : [x])
 , []);

reduce 遍历数组，对于它使用累加器（上一次调用的返回值）和当前元素调用每个元素。 concat 将当前元素添加到累加器（如果尚不存在）。 查找通过比较 ordersNo 属性来检查当前元素是否在累加器中。

reduce goes through the array, and for each element it calls the provided function with accumulator (the return value of the previous call) and the current element. concat adds the current element to the accumulator if it doesn't exist there yet. find checks if the current element exists in the accumulator by comparing the ordersNo properties.

演示：

const data =           [
        {
          "objectId": "WMtwbyhFI6",
          "cuisineNameEn": "Cafe",
          "ordersNo": 20,
          "hidden": false
        },
        {
          "objectId": "QJSNTMpq5F",
          "ordersNo": 24,
          "cuisineNameEn": "Italian",
          "hidden": false
        },
        {
          "objectId": "iLXKswFRGa",
          "ordersNo": 5,
          "cuisineNameEn": "Japanese",
          "hidden": true
        },
        {
          "objectId": "Db0MeihpJE",
          "ordersNo": 6,
          "cuisineNameEn": "Fast Food",
          "hidden": false
        },
        {
          "objectId": "QJSNTMpq5F",
          "ordersNo": 24,
          "cuisineNameEn": "Italian",
          "hidden": false
        },
        {
          "objectId": "Db0MeihpJE",
          "ordersNo": 6,
          "cuisineNameEn": "Fast Food",
          "hidden": false
        },
        {
          "objectId": "Db0MeihpJE",
          "ordersNo": 6,
          "cuisineNameEn": "Fast Food",
          "hidden": false,
        },
        {
          "objectId": "Db0MeihpJE",
          "ordersNo": 6,
          "cuisineNameEn": "Fast Food",
          "hidden": false
        },
         {
          "objectId": "Db0MeihpJE",
          "ordersNo": 6,
          "cuisineNameEn": "Fast Food",
          "hidden": false
        },
         {
          "objectId": "Db0MeihpJE",
          "ordersNo": 6,
          "cuisineNameEn": "Fast Food",
          "hidden": false
        },
        {
          "objectId": "Db0MeihpJE",
          "ordersNo": 6,
          "cuisineNameEn": "Fast Food",
          "hidden": false
        }
      ];
 
 console.log(data.reduce((acc, x) =>
   acc.concat(acc.find(y => y.ordersNo === x.ordersNo) ? [] : [x])
 , []));

这篇关于Javascript-仅返回对象数组中的唯一值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！