Saxon » SaxonJS

When maps are merged with keys involving timezone-adjusted values, under advanced closure compiler optimisation, duplicate key errors can be raised, which are not under simple optimisation (i.e. SaxonJS2.debug.js). map-size-014 is an example. The issue is in HashTrie/stdOptions/sameKey#41:

 return ("timezoneOffset" in n) && n.timezoneOffset !== null;

where under CC advanced optimisation the property timezoneOffset has been renamed, and thus the "timezoneOffset" in n check fails. The intention seems to be to only check if there is a timezoneOffset defined, and it is not null. Simply changing to

timezoneOffset.n && n.timezoneOffset !== null;

corrects these faults but introduces three others, in same-key-02[67] and MapConstructor-042.

This might be rather tricky without 'reserving' the timezoneOffset property - trying to determine the existence of renamed properties.