Javascript - 仅返回对象数组中的唯一值

时间：2017-12-29 14:59:56

标签： javascript arrays

我有一个对象数组，我想根据它们的对象Id返回唯一的对象。

我试图在现有数组data中循环，然后查找该元素是否已添加到新创建的数组arr，该数组应仅包含唯一值，但它不起作用和我在一起，我相信我在这里或那里都缺少一些东西。

以下是当前数组： 

          [
        {
          "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
        }
      ]

然而，这是我想要回归的内容： 

 [
        {
          "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
        }
      ]

我尝试了以下内容：

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

然而，它没有用。

6 个答案:

答案 0 :(得分：2)

使用reduce() method：

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

reduce遍历数组，对于每个元素，它使用accumulator（前一个调用的返回值）和当前元素调用提供的函数。 concat如果当前元素尚未存在，则将当前元素添加到累加器。 find通过比较ordersNo属性来检查累加器中是否存在当前元素。

演示：

＆＃13;
＆＃13; 
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])
 , []));
＆＃13;
＆＃13;
＆＃13;

答案 1 :(得分：1)

您可以filter数组并使用一组ID来检查欺骗：

const result = array.filter( (hash => obj => !(hash.has(obj.objectId) || hash.add(obj.objectId) && false))(new Set));

答案 2 :(得分：1)

您可以使用array#reduce创建一个以objectId为键，对象为值的对象。有了对象后，使用Object.values()提取所有值以获取唯一对象。

var 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 } ],
    result = Object.values(data.reduce((r,o) => (r[o.objectId] = o, r),{}));
console.log(result);
.as-console-wrapper { max-height: 100% !important; top: 0; }

答案 3 :(得分：1)

indexOf()无法检查类似对象或检查对象内的属性。它只适用于相同的对象引用

可以使用将公共属性存储为键的hashmap对象。以下使用this filter参数作为hashmap

＆＃13;
＆＃13; 
const res = data.filter(o => !this[o.objectId] && (this[o.objectId]=true), {});

console.log(res);
＆＃13; 
<script>
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
        }
      ];
</script>
＆＃13;
＆＃13;
＆＃13;

答案 4 :(得分：0)

您应该尝试使用过滤器和设置：

result = (function () { // we use an IIFE to isolate everything
    var uniqIds = new Set(); // Set only accepts unique values
    return list.filter(item => { // Array filter returns a new array based on result of callback passed in parameter
        if(!uniqIds.has(item.objectId)) {
            uniqIds.add(item.objectId);
            return true;
        } else {
            return false;
        }
    });
}());

答案 5 :(得分：0)

您也可以使用此简单的解决方案

function uniqueObjectsArr(array, uniqueValue) {
    var obj = {},
    uniqueArr = [];
    array.forEach(element => {
        obj[element[uniqueValue]] = element;
    });
    for (var key in obj) {
        if (obj.hasOwnProperty(key)) {
            uniqueArr.push(obj[key]);
        }
    }
    return uniqueArr;
}

 myData = uniqueObjectsArr(myData, "objectId");
 console.log(myData);
 <script>
 myData = [
        {
          "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
        }
      ]
      </script>

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