To see the demo, start a web server and load this page (e.g., `npx http-server` and navigate to http://127.0.0.1:8080/demos/fonts/core-with-promise.html).

Using vexflow-core.js allows your webpage to load a small initial bundle. It will load fonts on demand when you call Vex.Flow.fetchMusicFont(fontName). This method is asynchronous and returns a Promise.

Open your browser's developer tools to see that font modules are downloaded upon request:

View the page's source.

See: core.html
See: all.html