DateFormat.d constructor
The named constructors for this class are all conveniences for creating instances using one of the known "skeleton" formats, and having code completion support for discovering those formats. So,
new DateFormat.yMd("en_US")
is equivalent to
new DateFormat("yMd", "en_US")
To create a compound format you can use these constructors in combination with the "add_*" methods below. e.g.
new DateFormat.yMd().add_Hms();
If the optional locale is omitted, the format will be created using the
default locale in Intl.systemLocale.
Implementation
DateFormat.d([locale]) : this("d", locale);