File Type scripting editor has no script type dropdown... It does have a modifier @script, but the docs don't mention jscript. It does work.... so I don't have a question (yet).
Suggestion: Mention this wherever relevant, for example...
http://127.0.0.1:36787/v12.23/index.html#!Documents/Scripting/Simple_Script_Function.htm
Could mention adding
@script:jscript
Before
function OnClick(clickData) {
When using the File Type Editor.
Also, docs search for @script has no results.