This exercise is derived from chapter three of A Modern Introduction to Programming with JavaScript and jQuery, which tells the story of crazy Aunt Emily and her fifty plus cats.
The file cats.js contains a JavaScript function that returns an array of emails from Aunt Emily. jQuery is used here to display these messages one at a time in response to button clicks. It also provides an easy to understand example of conditional branching at work in determining what message to display on the button and when to stop incrementing the click counter.