Question

假设有两个数组

Array 1是我的Firebase Objects JSON数组，如下所示：

"players" : [
       {"name" : "YB", 
        "Team" : "Industry",
        "id": 1, 
        "position": "forward",
       {"name" : "Harry",
        "Team" : "Industry", 
        "id": 2, 
        "position": "defender",
        {"name" : "Honey",
        "Team" : "Industry", 
        "id": 3, 
        "position": "defender",
        {"name" : "abel",
        "Team" : "Industry", 
        "id": 4, 
        "position": "defender",
        {"name" : "Shaka",
        "Team" : "Industry", 
        "id": 5, 
        "position": "defender",
        {"name" : "ben",
        "Team" : "Industry", 
        "id": 6, 
        "position": "defender",
        {"name" : "randy",
        "Team" : "Industry", 
        "id": 7, 
        "position": "defender",
        {"name" : "john",
        "Team" : "Industry", 
        "id":8 , 
        "position": "defender"
         }
       ]

数组2为

[1,2,5,4,8,6]

有没有一种方法可以遍历array 1，特别是对象属性id，以搜索array 2的值，然后仅生成具有以下内容的对象的结果数组： id 1,2,5,4,8,6（即，只有具有id属性值与array 2中的值相对应的对象的数组）

我对javascript / firebase云功能很陌生，想知道如何实现。我在下面尝试了映射功能：

var produce = array1.reduce (function(acc,next) {acc [next.id] = next; retrun acc;}, {});

var combine = array1.map(function(num){return produce[num];});

但是它一直返回错误消息a rray1.map is not a function。必须使用地图function.

来实现此目标的更简单方法

Answer 1

您可以使用.filter()来过滤记录，并使用id在第二个数组中检查.includes()：

let data = [
  {"name" : "YB",    "Team" : "Industry", "id": 1, "position": "forward"},
  {"name" : "Harry", "Team" : "Industry", "id": 2, "position": "defender"},
  {"name" : "Honey", "Team" : "Industry", "id": 3, "position": "defender"},
  {"name" : "abel",  "Team" : "Industry", "id": 4, "position": "defender"},
  {"name" : "Shaka", "Team" : "Industry", "id": 5, "position": "defender"},
  {"name" : "ben",   "Team" : "Industry", "id": 6, "position": "defender"},
  {"name" : "randy", "Team" : "Industry", "id": 7, "position": "defender"},
  {"name" : "john",  "Team" : "Industry", "id": 8, "position": "defender"}
];

let matchIds = [1, 2, 5, 4, 8, 6];

let result = data.filter(({ id }) => matchIds.includes(id));

console.log(result);

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Answer 2

从错误中可以推断出您要映射的变量不是数组。
假设firebase响应具有以下格式：

var result = {"players":[
                           {"name" : "YB","Team" : "Industry", 
                            "id":1,"position":"forward"},
                           {"name" : "Harry","Team" : "Industry", 
                            "id": 2,"position": "defender"}
                          ]
              }

然后，让第二个数组如下：

  var array2 = [1,2,5,4,8,6];

因此，“结果”变量实际上是此处的对象，而不是数组。在这种情况下，我们可以尝试执行以下操作，以防止出现问题中提到的错误：

var finalResult = result.players.filter (function(player) {
                  return array2.indexOf(player.id) > -1;
              });

如何将一个数组值再次映射到另一个数组以产生结果

2 个答案: