I have simple HTML code with some javascript, it looks like:
I just wanted to be able to change the div's content (it's inner html) with selecting one of "A" or "B" radio buttons, but div#content does not have javascript attribute "value", so I am asking how it can be done.
Assuming you're not using jQuery or some other library that makes this sort of thing easier for you, you can just use the element's innerHTML property.
document.getElementById("content").innerHTML = "whatever";