将侦听器添加到Firebase生成的密钥中的子项？

根据您的评论更新答案。

您想听

/activity/$theid/thread/$threadId

与其嵌套，不如嵌套

/thread/$threadId

{  "threadActivity": {     "$activityId": {        "$threadId" : {        }      }   } }

现在，当添加新线程时，您可以只听

/threadActivity/$activityId

var ref = new Firebase('https://<my>.firebaseio.com/threadActivity');var activityRef = ref.child('some-id');activityRef.on('child_added', function(snap) {  // will update you for every child at the location and each child added  console.log(snap.val()); });