Rule of thumb:
Rails by default prints datetime in ISO8601 format in %Y-%m-%d %H:%M:%S +offset
style, e.g. 2014-12-18 13:00:00 +1000
and encode datetime in JSON as standard_son_format, e.g. 2005-02-01T05:15:10.000-10:00
Angular formats datetime in timezone of the browser if timezone option of date filter is not specified.
Browsers format datetime string based on local date format settings. But browsers only support datetime-local picker.
With Rails datetime_local_field, the timezone is ignored, it outputs something like this <input type="datetime-local" value="1984-01-12T00:00:00" />
.