JavaScript 2.0-The Complete Reference, Second ... - freecodingtutorial

A rendering of the example is shown next.
One thing that is rather troublesome with this detection is that the availHeight and availWidth
properties indicate the height and width of the screen minus any operating system chrome
rather than, as one might expect, the actual size of the available browser window. In order to
detect actual window size, you have to use properties of the Window object in the case of
Netscape. In the case of Internet Explorer, you need to look into the Document object and
examine the body itself. However, in the case of the DOM, you might want to look at the size of
the root element, namely, the tag, and not the if you are trying to get the
dimensions of the window. Of course, which tag to look at depends on what rendering mode
your browser is in, either loose or strict, which is generally determined by the doctype
statement in the document. This example shows how you might check all this. Invariably,
something might change given the lack of agreement among browser vendors on how to
implement certain CSS, XHTML, and JavaScript ideas, but the example should still
demonstrate the concept:
Available Region Checker
Resize your browser window