Why do functional pseudos such as :not() and :has() allow quoted arguments?
问题 Apparently, as I've discovered while commenting on another answer, jQuery (rather its underlying selector engine Sizzle) lets you quote the argument to the :not() selector as well as the :has() selector. To wit: $('div:not("span")') $('span:has("span")') In the Selectors standard, quotes are always representative of a string and never of a selector or a keyword, so quoting the argument to :not() is always invalid. This will not change in Selectors 4. You can also see that it's non-standard