inputDateFormat property
The date format in the input boxes when not selected for editing.
Defaults to %e %b %Y.
This is used to determine which type of input to show,
datetime-local, date or time and falling back to text when
the browser does not support the input type or the format contains
milliseconds.
API Docs: https://api.highcharts.com/highcharts/rangeSelector.inputDateFormat
Implementation
String? inputDateFormat;