I hope i'm not being wooshed here....
Firstly, HTML and javascript are seperate. To use a car analogy, think of a gas can. You have a gas can, and then you have the gas in it. The HTML is just a delivery mechanism and container for the javascript. Both HTML and javascript are based on standards, and there is nothing in either of the standards trying to screw the user out of copy/pasting text.
Go to maps.google.com. Right Click on the map. See how it presents you with a few options? Now, instead of presenting that menu, display nothing, and pop up a ransom box. Delselect text, and bam! done! Do the same for ctrl+c, and you have defeated 95% of the public.
So, this is not a javascript problem or an HTML problem. If this is a problem (I personally don't know), then it it a management being greedy problem.