如何展平这种阵列？答案

【问题标题】：How to flatten this kind of arrays?如何展平这种阵列？
【发布时间】：2020-10-06 20:52:47
【问题描述】：

我正在尝试展平一个数组，但在这方面遇到了一些问题。我有这些数据可供展平。

   arr =  [
    {
        "data": [
            [
                {
                    "_id": "5ee97ee7f25d1c1482717bdf",
                    "email": "test1@test.io",
                    "profileImages": [],
                    "username": "test1",
                    "birthday": "2020-06-11T10:11:32.000Z",
                    "phoneNumber": "+910000000000",
                    "location": "Test Location",
                    "firstName": "test1",
                    "lastName": "test1",

                }
            ],
            [
                {
                    "_id": "5ee97ef2f25d1c1482717be1",
                    "email": "test2@test.io",
                    "profileImages": [],
                    "username": "test2",
                    "birthday": "2020-06-11T10:11:32.000Z",
                    "phoneNumber": "+910000000000",
                    "location": "Test Location"
                }
            ]
        ]
    }
],

这就是我所拥有的......并且我希望这些数据以某种方式将数据合并到一个数组中，如下面的结构

data: [
           {
                "_id": "5ee97ee7f25d1c1482717bdf",
                "email": "test1@test.io",
                "profileImages": [],
                "username": "test1",
                "birthday": "2020-06-11T10:11:32.000Z",
                "phoneNumber": "+910000000000",
                "location": "Test Location",
                "firstName": "test1",
                "lastName": "test1"},
            {
                "_id": "5ee97ef2f25d1c1482717be1",
                "email": "test2@test.io",
                "profileImages": [],
                "username": "test2",
                "birthday": "2020-06-11T10:11:32.000Z",
                "phoneNumber": "+910000000000",
                "location": "Test Location"
            }
        ]

我曾尝试使用 lodash 库将其展平，但没有成功。对此有何建议，我如何将这些数组展平为单个数组？

【问题讨论】：

arr.flatMap(k=>k.data.flat())
flatMap 和 flat() 并未在所有浏览器中得到广泛支持。所以最安全的选择是使用简单的递归。看看下面的答案

标签： javascript arrays mongodb flatten

【解决方案1】：

您可以通过使用flatMap 和flat() 的组合来做到这一点，flat 将展平内部数组，而 flatMap 将用于外部数组。

var  arr = [ { "data": [ [ { "_id": "5ee97ee7f25d1c1482717bdf", "email": "test1@test.io", "profileImages": [], "username": "test1", "birthday": "2020-06-11T10:11:32.000Z", "phoneNumber": "+910000000000", "location": "Test Location", "firstName": "test1", "lastName": "test1", } ], [ { "_id": "5ee97ef2f25d1c1482717be1", "email": "test2@test.io", "profileImages": [], "username": "test2", "birthday": "2020-06-11T10:11:32.000Z", "phoneNumber": "+910000000000", "location": "Test Location" } ] ] }];

var result = arr.flatMap(obj=>obj.data.flat());

console.log(result);

我希望这会有所帮助。

【讨论】：

【解决方案2】：

你可以使用flat

var  arr = [ { "data": [ [ { "_id": "5ee97ee7f25d1c1482717bdf", "email": "test1@test.io", "profileImages": [], "username": "test1", "birthday": "2020-06-11T10:11:32.000Z", "phoneNumber": "+910000000000", "location": "Test Location", "firstName": "test1", "lastName": "test1", } ], [ { "_id": "5ee97ef2f25d1c1482717be1", "email": "test2@test.io", "profileImages": [], "username": "test2", "birthday": "2020-06-11T10:11:32.000Z", "phoneNumber": "+910000000000", "location": "Test Location" } ] ] }];

    console.log([...arr[0].data.flat()])

【讨论】：

【解决方案3】：

flatMap 和 flat() 并未在所有浏览器中得到广泛支持。看到这个：Search in multidimensional array (Algorithm)

所以简单的递归是最安全的选择。

var data = [
            [
                {
                    "_id": "5ee97ee7f25d1c1482717bdf",
                    "email": "test1@test.io",
                    "profileImages": [],
                    "username": "test1",
                    "birthday": "2020-06-11T10:11:32.000Z",
                    "phoneNumber": "+910000000000",
                    "location": "Test Location",
                    "firstName": "test1",
                    "lastName": "test1",

                }
            ],
            [
                {
                    "_id": "5ee97ef2f25d1c1482717be1",
                    "email": "test2@test.io",
                    "profileImages": [],
                    "username": "test2",
                    "birthday": "2020-06-11T10:11:32.000Z",
                    "phoneNumber": "+910000000000",
                    "location": "Test Location"
                }
            ]
        ]


  var result = [];
function flatten(data){
  data.forEach(k=>{
   if(Array.isArray(k)){
     flatten(k)
   }else{
    result.push(k)
   }
  });
  return result;
}
console.log(flatten(data))

【讨论】：