Can I create a script based condition in Eclipse that won't let me save a work item to a specific work flow step if all items in a checklist aren't checked?
One answer
As far as I can tell, conditions are not preventing save, unless used with the "read-only for condition" and similar preconditions.
You can try to write a validator if you insist on JavaScript this would validate the attribute containing the checkbox values. I would give it the chance of about 1%, I have never been able to get Javascript based attribute customization working for "List" attributes.
A Java Based validator would likely possible. But then you have to deploy the validator and then I would suggest to rather create an Advisor, a Java based Server extension for work item save operations. See the RTC/EWM Extensions Workshop. Also see https://rsjazz.wordpress.com/?s=Advisor&submit=Search for how advisors look like.