10/30/08 Notes

IT 130 -- 10/30/08

Write an HTML web page with a textbox, a button and an image that initially displays blank.jpg. When a number from 1 to 6 is entered into the textbox and the button is clicked, the page should display the corresponding image of a dog with its owner:

Ans: Here is the solution: dogowner.htm.

The builtin-in random number generator Math.random returns floating point numbers in the interval [0,1). This means that it can return 0 but it cannot return 1.
We want to write a JavaScript expression that returns random integers {1, 2, 3, 4, 5, 6} with equal probability.
We use Math.random and Math.floor together to accomplish this:
1. Math.random( ) returns a floating point in [0, 1).
2. 6 * Math.random( ) returns a floating point in [0, 6).
3. Math.floor(6 * Math.random( )) returns an integer in {0, 1, 2, 3, 4, 5}.
4. 1 + Math.floor(6 * Math.random( )) returns an integer in {1, 2, 3, 4, 5, 6}.
Use the following JavaScript statement to get a simulated roll of a fair die:

Look at these dice examples:
Here are the six dice images:
Normally you should not access images on someone elses website; multiple hits on their site will tie up their server. Place images on your site instead.
For Project Proj5, you have permission to access the lotto balls on Jost's website. Here is a link to the lotto balls folder:

An example that shows how to use a dropdown menu in three different ways:
An example that displays a random integer from the maximum value set in a dropdown menu:

Work on Project Proj5.
Use the Dice2 and PickRandom Examples as models.
Normally you should not access images on someone elses website; multiple hits on their site will tie up their server. Place images on your site instead.
However, for Project Proj5, you have permission to access the lotto balls on Jost's website. Here is a link to the lotto balls folder: