In my book that's all covered by the term 'dead code elimination', e.g. removing (or not including in the first place) any code that can be statically proven to be unreachable at runtime. Some JS minifiers (like Google's Closure) can do the same thing in Javascript on the AST level (AFAIK Closure essentially breaks the input code down into an AST, then does static control flow analysis on the AST, removes any unreachable parts, and finally compiles the AST back into minified Javascript). Tree-shaking without this static control flow analysis doesn't make much sense IMHO since it wouldn't be able to remove things like a dynamic import inside an if that always resolves to true or false.