This sample demonstrates the custom value functionalities of the ComboBox. When the typed character(s) is not present in the list, a button will be shown in the popup list. By clicking on this button, the custom value character is added in the existing list as a new item.
The ComboBox allows the user to give input as custom value which is not required to present in the predefined set of values. By default, this support is enabled by allowCustom property. In this case, both text field and value field are considered as same. The custom value will be sent to post back handler when a form is about to be submitted. More information about the Custom value feature can be found in the documentation section.