The issue is that, AFAIK, the ES import must include file extension. But imports in TS may not include it. And transpiler to JS didn't add some extension to the

The issue is that, AFAIK, the ES import must include file extension. But imports in TS may not include it. And transpiler to JS didn't add some extension to the import, making it invalid in JS. But I think that TS is still a superset of JS, even with this import thing. Because every valid JS file is valid TS file. To me that seems to confirm to definition of superset: A set A1 is a superset of another set B1 if all elements of the set B1 are elements of the set A1.