Version

persistCustomValues Property

enables / disables persisting of custom values. If some value that doesn't exist in the list is typed, and we remove the focus from the control, a new item is created, and marked IsCustom=true, and persisted to the server persisting of custom values SHOULD NOT be enabled along with loadOnDemand or Paging ! or with enables / disables persisting of custom values.
Syntax
ASP.NET Ajax Javascript (Specification) 
function get_persistCustomValues() : Boolean
ASP.NET Ajax Javascript (Usage) 
var resultVar = instanceOfWebDropDown.get_persistCustomValues();
See Also