Isn't that great? It's a simple, one-line script that does it. Here's the script:

     Get the above script all on one line...

     You can change what appears on the page by changing out where I have written "Place Your Mouse Here...". Each time a mouse hits it, the prompt box comes up and a message is created. If the person chooses not to enter anything or chooses "Cancel," the alert box says "Hello, Null." Strange, but that's what it says.