JSFiddle - React, Tailwind, and code Playground

JavaScript

var player = {
    setVolume: function() {
        $(this).trigger("volumeChanged");
    },
    
    addVolumeChangeHandler: function(fn) {
        $(this).bind("volumeChanged", fn);
    }
};

player.addVolumeChangeHandler(function() {
  alert("i will actually increase the volume.");
});

player.addVolumeChangeHandler(function() {
    alert("i will update the digital display.");
});  

player.setVolume();