CloudKit JS query with filter by modified date

Let me be the first to say this is probably not safe to use. I could not find any documentation on it and figured it out by brute force. I imagine Apple will replace this with a proper and documented method at some point in the future... but for now I've been able to filter on modification date by:

var query = {
     recordType: 'RECORD_TYPE',
     filterBy: [{
          comparator: 'COMPARATOR_FOUND_IN_APPLE_DOCUMENTATION',
          fieldName: '___modTime',
          fieldValue: {
               value: 1462661116582 // Milliseconds since 1970/01/01 as Integer.
          }
     }]
};

Good luck.