JavaScript Concepts.
this.ballCount = 1000; // No of balls in the game.
this.dropBallSpeed = 0.5; // At what speed the balls should drop.
this.dropBallFrequency = 500; // At what intervals next ball should drop after the previous one.
this.shootEvent = 'mouseover'; // can choose what you like, for tutorial 'click' is used, but mouseover is better.