If we open the console in Firefox and put:
{
test: 'test',
test: 'testtest'
}
Firefox would treat it as a block of code which would turn out to have an error due to unexpected colon. In the opposite Node repl and eg. Chrome interpret it as object declaration. I would say this is a bug but I don't know if I can say that - interpreting it as a block of code is somehow correct? Putting that declarations into another parens i.e. ({...})
works without any problem though but still it's misleading as other environments find out this is an object declaration