# Tracking the number of elements in a list
This template shows how to keep track of the number of elements in a Firebase Database list. For instance this can be useful to keep tack of the number of "likes" or "followers" of something shared on a social platform.
## Functions Code
See file [functions/index.js ](functions/index.js ) for the code.
This is done by updating a `likes_count` property on the parent of the list node which is tracked.
This counting is done in two cases:
1. When a like is added or deleted, the `likes_count` is incremented or decremented.
2. When the `likes_count` is deleted, all likes are recounted.
The dependencies are listed in [functions/package.json ](functions/package.json ).
## Sample Database Structure
As an example we'll be using the database structure shown below. It keeps tracks of the list of users who liked a post and the count of these likes:
```
/functions-project-12345
/posts
/key-123456
likes_count: 32
/likes
user123456: true
user456789: true
user786245: true
...
```
