Same as indexing timezoneAbbreviations directly but accepts any casing and surrounding
whitespace, and accepts a string that isn't an abbreviation at all. Returns undefined rather
than a guess when the abbreviation is unknown, so callers can fall back or alert instead of
silently picking a wrong offset.
Same as indexing timezoneAbbreviations directly but accepts any casing and surrounding whitespace, and accepts a string that isn't an abbreviation at all. Returns
undefinedrather than a guess when the abbreviation is unknown, so callers can fall back or alert instead of silently picking a wrong offset.