Elf Sternberg

I can take a pretty good guess as to the 19-century gap. Many programming languages and libraries written in the 20th century only used the last two digits of the year. In order to have the year numbers always increasing and to avoid ambiguity as one enters the second half of the 21th century while remaining compatible with old code, the year value used by the library was respecified as the actual year minus 1900. Probably, Elf's function expects the year-1900 hack, and some browsers are just giving the year. A quick fix would be to compare the browser-given year to 1000, if less than assume the year-1900 hack has already been applied, else assume it has not and apply it yourself. (Though, strictly speaking this "solution" will have changed at least every 1900 years, no matter what value is used for comparison.)