Extendscript variables undefined when triggered from PostFrameMakerDocUpdate event

Question

I am trying to run an Extendscript script in RH10.0.1.292.
This script is registered to the PostFrameMakerDocUpdate event so that it runs evey time I update my FM sources.
Every time I Update or Force Update, when the script runs, I get an 'undefined variable' message.
However, when I run the same script from within  RoboHelp, or from the ExtendScript Toolkit, everything is fine. The script runs to completion without any errors.
Initially, the undefined variable is a global (defined at the top of the file before any functions)
var Rev = "Rev 2.3 December 22, 2013";
If I move Rev into the only function where it is used, I get another error: the numParaStyles is now an undefined variable. This is a local variable, defined in the one and only function where it is ued.
var numParaStyles = FM_paragraphStyles.length;
Although FM_paragraphStyles is a global array:
var FM_paragraphStyles = ["TipText", "CautionText", "WarningText"];
This script is is based on the Reference Page Image Updater.jsx script included in the
Adobe\RoboHTML\10.00\Scripts\Sample Scripts
folder. I added the Rev string as part of my debugging efforts,
Since the script works find from the ExtendScript Toolkit and from within RoboHelp, I suspect something is happening to mess up with the script's variable scoping when the script is run in response to an event. But that's just a guess. I am not an expert in JavaScript, let alone ExtendScript.
Has anyone else seen this behavior? Is there something I can do to prevent the error messages?
Thanks!

Answer 1

Extendscript doesn't work nice with globals if you are using scripting
events. In my experience, the easiest workaround is to create functions
that create globals and call that function in the function linked to an
event. Personally, I normally make a script and then add an extra
function specifically for events that initiates any globals and then
runs the script normally. There's no easy fix, sorry.
I believe this is a bug. You can report bugs to Adobe via
https://www.adobe.com/cfusion/mmform/index.cfm?name=wishform
Kind regards,
Willam