It needs to be rewritten, unfortunately. However this isn't just rewriting it so it works with one tool, since this is the new module syntax. I imagine that a future version of jQuery, and probably most libraries going forward, will want to take advantage of ES2015 modules, even if it's just to aid in their own internal development. Since we have module bundlers like rollup, it would be easy to still provide an ES5 bundle for environments that do not use ES2015 modules yet.