javascript - 获取对象属性的长度，该对象属性是对象数组的属性

Question

所以，我想获取对象属性的长度，该对象属性是对象数组的属性。

我想获取actionDetails的长度。

我尝试了以下操作:message[0].actionDetails[0].length;但这会导致未定义。

数据如下:

message=   [  
       {  
          "data":"1",
          "actionDetails":[  
             {  
                "type":"action",
                "url":"http:\/\/localhost\/app\/dashboard"
             },
             {  
                "type":"action",
                "url":"http:\/\/localhost\/app\/dashboard"
             },
             {  
                "type":"action",
                "url":"http:\/\/localhost\/app\/dashboard"
             }
    ]

Answer 1

I tried the following: message[0].actionDetails[0].length; but this is resulting in undefined.

差不多到了，你不需要先获取你要查找长度的数组的第 0 索引

message[0].actionDetails.length;