MDN explains how to use the window.screen object, but also says “DOM Level 0. Not part of specification.“
W3Schools says that window.screen.* properties are supported in all major browsers.
If I understand this correctly… window.screen is completely non-standard, but is nonetheless universally supported. Is that right?
If this is the case, are there any cross-browser differences I need to be aware of, or can I just use it? I’m mostly interested in screen.availWidth, by the way.
Quirksmode compatibility tables to the rescue!
http://www.quirksmode.org/dom/w3c_cssom.html#screenview
Most, but not all values are supported by the major browsers.