ball-animation-object.js

// global variables that will be loaded/initialized later
let canvas, ctx, gravity, ball, friction

function init () {
  // our canvas variables
  // ...
  // set the canvas size
  // ...
  // world/scene settings
  // ...

  // starting objects
  ball = {
    bounce: 0.75, // energy lost on bounce (25%)
    radius: 30,
    x: canvas.width / 2,
    y: canvas.height / 2,
    velX: (Math.random() * 15 + 5) * (Math.floor(Math.random() * 2) || -1),
    velY: (Math.random() * 15 + 5) * (Math.floor(Math.random() * 2) || -1)
  }

  // begin update loop
  // ...
}