Javascript Can'；我不明白为什么ng repeat不排序

我有以下HTML，我想按最新注释按时间倒序排序：

<div class="list list-inset"
    ng-repeat="(threadId, thread) in messageThreads | orderBy:'thread.newestComment'"
    ng-if="thread.newestComment > messageClearTime">
    <div class="item item-divider">
        {{thread.newestComment}}
    </div>
</div>

---

无论我做什么，我似乎都不知道如何进行排序——它总是按照数组的顺序出现。有什么帮助吗？

orderBy过滤器仅适用于对象数组，而不适用于对象本身。见文件

{ "5381897" : {
      "newestComment" : 1403280014,
      "title" : "asdf"
    },
  "5595015" : {
      "newestComment" : 1403192555,
      "title" : ""
    },
  "5761260" : {
      "newestComment" : 1403126044,
      "title" : ""
    },
  "5838498" : {
      "newestComment" : 1403279962,
      "title" : "Share Test"
    }
}