Convert MusicXML to MIDI in browser using music21j

Question

I'm trying to load music21j in the browser (successful), and then convert an uncompressed MusicXML string into a MIDI file using the converter (not successful).

<script> 
  import * as music21j from 'https://cdn.jsdelivr.net/npm/music21j/+esm';
  console.log(music21j.default.converter.parse());

  // now how do I pass a MusicXML string to music21j and get midi back?

</script>

The code above displays the message Loading Instrument: audio will begin when this message disappears in the HTML. However, I'm not trying to load any audio -- in fact, I'd like to avoid loading any soundfonts, and simply have music21j available as a conversion tool.

So, to summarize: how can I simply pass an XML string to music21j and convert it to MIDI?

Thanks for any clarification!