Hey @jh_st,
Thanks for sharing your question! It sounds like you may have skipped some of the steps of creating a component. The URL that’s passed to the declare_component method should be the address of the server where you’re hosting your component – it seems like in this case that URL might be the JS for WaveSurfer.
Check out our guide on building bidirectional components here. We also have TypeScript and React templates here.
Also worth noting that this forum post covers the simplest possible HTML component – you might be able to go with that route for this.