Why w3 validator says onClick is not valid?

Question

w3 validator gives me this error

there is no attribute "onClick"

I can't see what is making my code invalid.

<a href="#" onClick="return BookmarkApp.addBookmark(this)"><img alt="" src="./favorites-intro.jpg" /></a>

suggestions?

Answer 1

If you change it to lower case onclick, the error goes away. Like this:

<a href="#" onclick="return BookmarkApp.addBookmark(this)"><img alt="" src="./favorites-intro.jpg" /></a>