Javascript does not define the implementation details. It does not have to be interpreted, and in fact I don't believe any modern implementation is interpreted. Javascript is generally compiled to byte code which is then run in a VM, or native machine code (V8 at least does this). There is no reason javascript could not have a static type system, there are statically typed scripting languages. It is dynamically typed by deliberate decision, not "we can't do it any other way".
Javascript does not define the implementation details. It does not have to be interpreted, and in fact I don't believe any modern implementation is interpreted. Javascript is generally compiled to byte code which is then run in a VM, or native machine code (V8 at least does this). There is no reason javascript could not have a static type system, there are statically typed scripting languages. It is dynamically typed by deliberate decision, not "we can't do it any other way".