Magic Eight Ball engine in JavaScript: Teaching Computer Programming To Kids : Lesson #4

Cate wants to make a computer program be to be like the Magic 8 ball, in my last post, I couldn’t remember how to generate a random number. But found it here

Math is a class (not an object ), it has 2 class member functions.


which will give me a random decimal between 0 and 1, like 0.11, 0.34. If we take this and multiply by 6, then we will get a number between 0 and 6, but less than 6


will round off the decimal number to an integer.

Math.floor( Math.random() * 6)

So here is the program, which will magically give you an answer to any question you have in the word


<script type="text/javascript">
var question  = window.prompt("Ask a question! :)");
/* RFE: time thing change question after 5 secs, to ask the user to hurry up */

var magicAnswers = [
"Hazy, try again",
"No way",
"We'll see",
"Of course!",
/* Math.random() the computer makes a random number between 0 and 1, 
  gives you answer to your question
 multiply by 5 would give you a number between 0 and 4
 Math.floor makes the number a round number
var randAnswer = Math.floor(

window.alert("Q: " + question + "\n\n" + "A: "+ magicAnswers[randAnswer]); 


/* the engine of the Magic 8 ball game is simple and complete, some ideas 
for the UI
 1) have a wizard stand behind a crystal ball, ask a question, zoom in to
 the crystal ball and show the answer
 2) have a bouncing black eight ball, ask a question and the eight ball 
shakes a bit and shows the answer, it prompts you every 3-5 seconds.

 As another enhacement, we can keep a history of all the previous 
questions and answers. display the question a bubble next an avatar
 of the person asking follow by the answer 
almost like a comic strip
 This will allow us to see the previous history of all the funny 
question and answers

This is a series that documents my daughter’s curiosity to learn about computer programming