rabbit.js

function Rabbit() {
  this.color = "white";
  this.children = [];
}

Rabbit.prototype.pullFromHat = function() {
  return !!Math.floor(Math.random() * 2);
};

Rabbit.prototype.haveChildren = function() {
  for (var i = 0; i < 20; i += 1) {
    this.children.push(new Rabbit());
  }
};

var rabbit = new Rabbit();
alert(rabbit.pullFromHat());
rabbit.haveChildren();
alert("Number of children: " + rabbit.children.length);