Number of Elements added in DataTable

Hi All
I wanted to know how many number of elements added to DataTable
My Code looks like this

var count = new DataTable([‘Name’],[‘Number’]);
count.add(’[x]’,’[2]);
like this I will add the data.

Now I would like to know in calling function, how many elements are added
Tried with count.size and count.length both are not working

Any Solution please?