Picked one day ago, when is used in GMT+02:00

[nasko-m]

If is picked today, the result is yesterday.

if (options.useIsoDateFormat) { return new Date(year, month - 1, day, 0, 0, 0).toISOString().substring(0, 10); }

must be replaced with

if (options.useIsoDateFormat) { return new Date(year, month - 1, day, 0, - new Date().getTimezoneOffset(), 0).toISOString().substring(0, 10); }