Question

I don’t know jQuery, but it looks to me jQuery has an overwhelming number of selectors, way more than css2.1 selectors. So do jQuery support additional selectors in addition to supporting css2.1 selectors? Or jQuery selectors are actually css3 selectors, which is more than css2.1 selectors? Can I use Query selectors in css3?

Answer 1

jQuery supports most selectors from the CSS Selectors Level 3 specification, and it adds some of it’s own too. From the jQuery docs:

Borrowing from CSS 1–3, and then adding its own, jQuery offers a
powerful set of tools for matching a set of elements in a document.

An example of a jQuery extension is the :submit selector. Notice in the docs page it states:

Because :submit is a jQuery extension and not part of the CSS
specification, queries using :submit cannot take advantage of the
performance boost provided by the native DOM querySelectorAll()
method. For better performance in modern browsers, use [type="submit"]
instead.

There is a note like that on the page for every custom jQuery selector, so if you spend a bit of time browsing the jQuery selectors API you should soon get to grips with it.