Is it safe to use window.screen?

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 t开发者_如何学编程he 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.

You should be fine with it.

The reason that it is not part of a standard is because DOM Level 0 was introduced before standards were around. DOM Level 0 is also called the Legacy DOM, and it was created at the same time NetScape 2.0 made JavaScript in the browser a reality; in effect, DOM Level 0 was the very first DOM spec.

The Legacy DOM will be around for a long time, if not then it would break backward compatibility with a TON of very popular scripts already in existence.

EDIT: In other words, your understanding is completely correct. It is not "standardized" but it is completely universal and will remain so for a long time.