访问javascript对象中的数组键

我试图在javascript中访问对象内部的数组键

这是我的.js文件：

var contentData = [
            {
                tops: [
                            { image: "images/top1.jpg" },
                            { image: "images/top2.jpg" },
                            { image: "images/top3.jpg" },
                            { image: "images/top4.jpg" } ]
            }
    ];

$scope.objectArray = contentData;
$scope.objectCount = $scope.objectArray[0].length;

---

我试图访问“contentData”中的“tops”，以显示“tops”数组的长度，该数组应为四个您不指定

tops

属性。应该是：

> var contentData = [
...             {
...                 tops: [
...                             { image: "images/top1.jpg" },
...                             { image: "images/top2.jpg" },
...                             { image: "images/top3.jpg" },
...                             { image: "images/top4.jpg" } ]
...             }
...     ];
undefined
> 
> contentData[0].tops.length
4

 $scope.objectArray[0].tops.length;

---

应该是

$scope.objectArray[0].tops.length