Still working it through. The steps as I see it:<p>Figure out which browsers to support on which features: <a href="https:&#x2F;&#x2F;kangax.github.io&#x2F;compat-table&#x2F;es6&#x2F;" rel="nofollow">https:&#x2F;&#x2F;kangax.github.io&#x2F;compat-table&#x2F;es6&#x2F;</a><p>Have an alternate .babelrc with a transpile blacklist that points to a separate dest<p>Build a regex to match those browsers in your CDN (I use Fastly). Vary on the value you create.<p>Point said browsers asking for the normal JS payload to the alternate dest.