I have been reading over the JavaScript Scripting documentation located at JavaScript Scripting - Automation | openHAB
On this webpage I found this: .changedSince(timestamp, serviceId) ⇒ Number which I interpret as calling that method (if that is the right term) returns a number. That doesn’t seem to be correct, it returns a boolean.
The documentation on the GitHub site https://openhab.github.io/openhab-js/items.ItemHistory.html is correct, or at least different, as it states a boolean return.
Just wanted to give some feedback on the documentation, which I found to be very helpful.