The size read-only property of the RTCStatsReport interface returns the number of items in the current report.
Note that each item consists of a key-value pair, where the keys are unique id values for monitored statistics objects from which the statistics are derived, and the associated values are statistics dictionary objects.
This property is otherwise the same as Map.prototype.size.
An integer indicating the number of items in this report. The value is zero if the report is empty.