How to create a popup drop down list and update selected files

I want to update "GENRE" by customized drop down list which will be popup-ed by clicking on a button. Please help me to create a popup drop down list and update selected files.

I search the manual example
https://www.gpsoft.com.au/help/opus12/index.html#!Documents/Scripting/simpledialogsandpopupmenus.htm

https://www.gpsoft.com.au/help/opus12/index.html#!Documents/Scripting/scriptdialogexample.htm


But in this example code write in VBscript. But I want to do the same thing in JScript. How to do it.

helo every one, Please tell me where to start?