Returns true if a metric or KPI FactList contains no entries that have real values. If there are Facts in the list but they contain null or NaN values this function will return true. This is a useful function when developing new KPI formula as it can be used for simple debug logging.  

if (metrics.get('critical issues').isNull()){
    console.log('No critical issues for date: %s', now);
}
Did this answer your question?