The current implementation actually defaults to 'undefined', and there is a strict check if the timestamp is set to 'false'.
The result of this check (timestamp === false) will only be true if timestamp is 'false'. 'undefined' (default) will not result in this check evaluating to 'true'.
The current implementation actually defaults to 'undefined', and there is a strict check if the timestamp is set to 'false'. The result of this check (timestamp === false) will only be true if timestamp is 'false'. 'undefined' (default) will not result in this check evaluating to 'true'.