When using or, values are evaluated in a boolean context from left to right, just like and. If any value is true, or returns that value immediately.
'a' or 'b'
'a' is the first true, so return 'a' immediately
'' or 'b'
'b' is the first true, so return 'b' immediately
If all values are false, or returns the last value.
'' or [] or {} return {}