Now, let's see:
this text will be visible in your browser before you are prompted for a number

This text will not be displayed until after the script was completed

This is the most common way to get input from users, you can of course use this method inside some of the other protection techniques (encryption and frame-direct printing, for instance) that you'll learn later.

When this page is loaded, the text at the beginning, up until the first opening <script> tag, is displayed immediately. Then the script executes and prompts the user for a number. At this point, the document freezes until the user responds. After the user inputs a number num, the script writes numbers 1 through num to the document. When the script finishes, the rest of the document is displayed. This example demonstrates how a Web page can ask for user input while it is being loaded and then display content that depends on the user's response. This pattern can be extended so that JavaScript embedded near the top of the Web page prompts the user for a password. The user's response can then be used to decrypt the rest of the document, as you will see in my next essay (and has you have already seen coming to the "hyper" section).

Note also in the code the


if (isNaN (num))                num = null;

line. This function returns true if a value is not a number ("NaN").
You should by all means play a little with this code skeleton, add a series of if statements (for password checking purposes) and send here your best results...
Have you noticed that the small "javascript logo" above does NOT appear until the user has entered his number? This gives you some ideas, does not it? :-)

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