Very nice! It reminds me of these two loader experiments:
<a href="https://curiosity-driven.org/amd-loader-with-promises" rel="nofollow">https://curiosity-driven.org/amd-loader-with-promises</a>
<a href="https://curiosity-driven.org/minimal-loader" rel="nofollow">https://curiosity-driven.org/minimal-loader</a><p>But for production builds I highly recommend Almond: <a href="https://github.com/jrburke/almond" rel="nofollow">https://github.com/jrburke/almond</a>