I have design a template for Incident report, in which I create a custom field called affteced service allows end user to choose from drop down list name of service and base on what user has chose subcategory will change accordingly, because list contain a lot of item so I would like to ask your support for a Javascript which can help me execute that when end user select a service from affected service field, the subcategory will change (set) accordingly

thank you !

eg:

Affected service: Active directory - Subcategory: AD<<Incident

Affected service: email - Subcategory: Exchange<<Incident

Affected service: internet - SubCategory: Proxy <<Incident

...

...

and so on