Can anybody explain the advantages of switching to a functional language when it is not a pure one? For example, how is it better than Javascript? Is the uniformity of the syntax (and perhaps implicit currying) the main benefit?
Lisp isn't a functional language. It's a family of languages, most of which support more than one programming paradigm. Most languages that are identified as some kind of Lisp are strictly evaluated, do not support partial evaluation (explicit currying only), and support mutable variables and mutable aggregate objects.
I really disagree with the 21st century fashion to make everything that isn't a Miranda derived language as not being a FP language.