Right: "If any part of LIST is an array, foreach will get very confused if you add or remove elements within the loop body, for example with splice. So don't do that"

Except in my case I found that if all you have is a single array as your loop list and you only modify it by push-ing new elements on to the end, the foreach in fact does not seem to get confused.

My question is is this use case safe or was I lucky?

Maybe the phrase 'in general' in the OP was too general. I am only asking about cases where the loop list consists solely of a single array.