Javascript Audio Objects in Ionic

I’m currently building an iOS app that can play 30 second previews of songs from Spotify. Javascript Audio objects work great and have been playing absolutely fine across several weeks of development, but I’ve just created a preloading script and it is not called at all when the app is running on my phone or Simulator. With Ionic Serve on Safari, the app function works as expected.

Is this supposed to happen? Does Ionic not recognise ‘audio.oncanplaythrough’ on purpose?