Firebase child_added 仅添加子项

Question

来自 Firebase API:

Child Added: This event will be triggered once for each initial child at this location, and it will be triggered again every time a new child is added.

一些代码:

listRef.on('child_added', function(childSnapshot, prevChildName) {
    // do something with the child
});

但是由于此位置的每个子项都会调用该函数一次，有什么方法可以只获取实际添加的子项？

Answer 1

要跟踪自某个检查点以来添加的内容而不获取以前的记录，您可以使用 endAt() 和 limit() 来获取最后一条记录:

// retrieve the last record from `ref`
ref.endAt().limitToLast(1).on('child_added', function(snapshot) {

   // all records after the last continue to invoke this function
   console.log(snapshot.name(), snapshot.val());

});