The formatting methods provided by Formatter are all named in the form of asXyz().
The behavior of some of them may be configured via the properties of Formatter. For example,
by configuring [[dateFormat]], one may control how Formatter::asDate formats the value into a date string.
Formatter is configured as an application component in Application by default.
You can access that instance via Yii::$app->formatter.
The Formatter class is designed to format values according to a [[locale]]. For this feature to work
the PHP intl extension has to be installed.
Most of the methods however work also if the PHP intl extension is not installed by providing
a fallback implementation. Without intl month and day names are in English only.