Firefox doesn't support
document.all. Or does it?
Beware: Firefox does sport a
document.all when a page is in quirks mode. In fact, you can see it with the DOM Inspector tool. It doesn't have any child elements so I suspect it's some sort of wrapper for
getElementById. Try referencing it from code and you may get this friendly warning:
Warning: Non-standard document.all property was used. Use W3C standard document.getElementById() instead.
Switch to a standards-compliant page and
document.all is undefined, as expected.
Obviously this puts code that employs quick old-school browser checking with Updated: see below.
document.all at risk — especially if your code is meant to be portable or drop-in.
Update: looks like support for document.all was introduced in Moz 1.7.5 back in December 2004.
Update #2 Confusion. The Mozillazine note says the document.all is "undetectable", but the way I discovered this was because FF was taking an IE code path based on the existence of document.all, exactly what shouldn't be happening. So I dunno.
Update #3 I haven't been able to reproduce the case that led me to discover Firefox's
document.all implementation, so I think the bug must have been in my code. (Shocking, I know!) In any case, it does look like a test for
document.all in Firefox should return false.