You're looking at the wrong side of it. The subtraction does behave in a perfectly logical manner. The problem is that, given the the behavior of the subtraction operator, the addition operator's actions are illogical. Specifically, I'd argue it's perverse because it breaks commutativity:
'5' + 3 - 3 != '5' - 3 + 3
The logical approach would be to only assume that '+' is a string concatenation if both operands are strings and otherwise type coerce into numbers. Then:
'5' + 3 = 8
'5' - 3 = 2
To someone who doesn't code Javascript for a living, the above seems like a far more consistent and useful behavior.
'5' + 3 - 3 != '5' - 3 + 3
The logical approach would be to only assume that '+' is a string concatenation if both operands are strings and otherwise type coerce into numbers. Then:
'5' + 3 = 8 '5' - 3 = 2
To someone who doesn't code Javascript for a living, the above seems like a far more consistent and useful behavior.