There is a ... "movement", if you will, to
promote better JS documentation. I have seen this banner on sites such as thechangelog.com.
So far I have no recollection of receiving wrong information from w3schools. But they have also never been my only source of information. For ze Germans there is the superb and unmatched
SELFHTML, which seems a little outdated:
SELFHTML: Version 8.1.2 vom 01.03.2007
Selfhtml has examples for virtually everything, and it's all hyperlinked. For many this is the one-stop reference work.
I tend to use w3schools less and less these days for two reasons: bad press from many opensource sites that employ the banner you see above; and because I do less and less web stuff (and I feel great about it!)