The simple rule is that primitives are passed-by-value and complex (objects) are passed-by-reference. Types that act like primitives (String, Number, Boolean, etc...) when created using the new keyword are complex objects and will be passed-by-reference but many of the operations that can be done on those will coerce the result to a primitive.

Pretty similar to mine though your start product code is nicer. Good job!

Love this one but the directions said specifically to return true/false. It is an easy fix though just add '!!()' around your logic checks to force a conversion to an actual boolean. Much more compact than mine, great job!