SICP is about exploring various programming concepts and paradigms like functional, object-oriented, constraint-based, lazy evaluation and so on. Scheme happens to be the perfect vehicle for this, since its support for code-as-data makes it much easier to implement new sub-languages and evaluation forms.

SICP is not about learning any particular language, it is about learning concepts which will make you understand JavaScript much better than anyone who only knows JavaScript.

If having to learn a new language like Scheme is an impediment to starting SICP, then you will not get past the first chapter anyway.