Start with this:
var arr = [{a : 1}, {b : 2}, {b : 2}, {b : 2}]
var dataset = new recline.Model.Dataset({
records: arr
});
dataset.recordCount // returns 4
dataset.records.reset() //all records are gone
but dataset.recordCount is still 4
Remember that the records attribute on a Dataset just represents a partial "window" of records from the full set of records stored in the associated backend.
Changing records will have no affect on the backend unless you save and requery.
Remember: recordCount is total number of records in the backend not the total in the .records list.