We often need to show a progress when the user clicks s button to start something like loading or saving something. One way is to show the user a progress dialog. Another way is to show the progress directly in the button. These kind of buttons are called ladda buttons (https://lab.hakim.se/ladda/)
We ported the concept of ladda buttons to JavaFX.
https://github.com/UltraMixer/LaddaFX