Unclear Documentation on Data Update and Data Deletion

JavaScript
1

In the document section of object deletion and object updates, what does the contactStorage object refers to?
The examples are not clear.
https://backendless.com/documentation/data/js/data_deleting_data_objects.htm

2

“contactStorage” refers to the object retrieved with “Backendless.Persistence.of( Contact )”

3

I could understand it after spending some time here. But updating the document section would be helpful for many new comers like me.